Drive Is Not Accessible. The Parameter Is Incorrect.
Do Not Format the Volume

Windows reached your partition & then gave up inside it. The partition table was readable, the volume driver started the mount, & something it read back out of the volume was a value it could not use. That is the whole message.

Four layers sit between the drive letter you clicked & the platters. The error tells you the top one failed. It does not tell you which of the lower three caused it.

Windows system error 87

ERROR_INVALID_PARAMETER. The volume driver rejected the mount because a value it read from the volume was invalid, so the refusal happens before any of your files are read. Nothing about the code identifies a cause.

Volume boot record

The first sector of the NTFS volume. It carries the cluster size, the volume length, & the location of the master file table. When those fields do not parse, Windows never finds the file table, & the mount stops there.

$MFT and $MFTMirr

The master file table & its mirror. Every file & directory on an NTFS volume exists as a record inside it, & Windows parses records from it during the mount. A record that does not parse halts the mount even when every byte of your file data is untouched behind it.

Unreadable sectors

Bad sectors are always a physical media symptom, never a file system one. If the sectors holding the boot record or the file table cannot be read, the parameter error is the downstream symptom of failing hardware, & the metadata above it may be perfectly intact.

The log entries were written while the drive was still trying. That makes them better evidence than anything you can collect now, & collecting them does not spend a single read on the patient drive. Work through these in order, on the machine the drive was connected to.

1. Open Event Viewer with the drive disconnected. Run eventvwr.msc, open Windows Logs and then System, & read the disk & Ntfs entries from the window when the volume stopped mounting. Event ID 55 puts the fault in the NTFS structures. Event ID 153 puts it in the hardware, because a retried I/O operation means the drive did not answer the first time. Event ID 157 means the disk dropped off the bus mid-operation.
2. Read Disk Management without mounting the volume. A drive that reports its correct capacity & its original partition layout, with the volume shown as its real size, points at the metadata layer. A drive that reports the wrong capacity, shows the space as unallocated, or vanishes from the list partway through a refresh points at the hardware layer.
3. Listen to it, once. Clicking, beeping, or a spin-up that gives up & winds back down is a mechanical fault, & the error string is beside the point at that stage. Power it off. See clicking hard drive for what that sound is.
4. Remember how the drive behaved last week. Directory listings that hung, Explorer freezing on a folder, file copies that stalled on one file & then resumed: that history is read retries, & retries are the hardware side of this error. A volume that performed normally until the day it stopped mounting leaves you no retry history, so the log entries carry the whole decision.
5. Count the attempts you have already made. Every mount attempt, scan, & repair pass on a drive with degrading heads spends readable sectors & head life on a diagnosis you can get from a log file instead.

Checks That Are Unreliable Over USB

Two of the standard checks stop meaning what you think they mean the moment a USB bridge is in the path.

• An empty SMART table. Some USB-to-SATA bridge implementations do not pass SCSI/ATA Translation commands through to the drive. A SMART tool then reports nothing for a drive that is logging errors internally, so an empty table read over USB is not evidence of a healthy drive. Read SMART with the drive connected directly instead, & see SMART errors for what the attributes mean.
• Advice that starts with take it out of the enclosure. That works on external drives built around a standard SATA drive & a separate removable bridge daughterboard. Many modern portable USB drives instead carry the USB connector & the bridge controller on the drive's own PCB, with no SATA edge connector to reach, so there is nothing to unplug & a native connection becomes board-level work. Check which one you have before opening anything.

The common advice for this error string is a fixed list: chkdsk /f /r, sfc /scannow, reinstall the storage driver, assign a new drive letter, & format if none of that works. Two items on that list are irrelevant, one is harmless, & the last two are the ones that lose data.

SFC checks Windows system files, not the metadata inside a data volume, so it cannot repair what error 87 is reporting. Reassigning a drive letter changes a mount point, not a single byte inside the volume. Neither one is dangerous, & neither one is a fix.

CHKDSK is where the accuracy matters, because it is misdescribed in both directions. CHKDSK runs over standard ATA at the file system layer; it cannot access the drive's firmware Service Area & it does not overwrite the translator. What it does is command the drive to read, & keep reading, across a surface that is already struggling.

On a drive whose heads are degrading, sustained read retries mechanically stress those heads & score the platters. That is the cost of running it on the wrong drive, & the cost is paid in the parts of the surface that were still readable when you started. On top of that, chkdsk /f writes its corrections into the file table it is judging, which is the same structure a lab reads to rebuild your directory tree.

The format prompt is the faster loss. A quick format writes a new, empty $MFT at the volume's MFT location rather than leaving the old metadata in place, so the beginning of your file table is gone the moment you click through.

File data further into the volume often survives, which is why carving sometimes returns files after a format, & why it returns them without names, folders, or directory structure. See corrupted hard drive recovery for the file system side of that work.

Every path starts the same way & then splits on what the drive is doing physically. We never repair a file system on the patient drive; the drive gets write-locked & imaged first, & the file system work runs against the image afterward. That order is what keeps a wrong guess about the cause from costing you data.

The write lock ordering is the part most DIY workflows get backwards. A hardware write blocker between the host & the drive stops your computer from writing, & that is worth having, but the drive keeps doing its own internal work behind it. Commanding the lock in firmware on the PC-3000 stops that too.

PC-3000 & DeepSpar Disk Imager are separate tools doing separate jobs here. The PC-3000 handles drive-level & firmware-level access; DeepSpar images the surface with tight timeout control so a drive that stalls for seconds on a bad read gets cut off & moved on instead of grinding.

Neither one parses NTFS. That is software work on the finished image.

When the Media Is the Problem

Dense unreadable sectors change the goal. The job stops being a clean full image & turns into getting the highest-value regions off first: the metadata, then the directories you named as priorities, then the rest of the surface in passes with adjusted read parameters. See bad sectors data recovery for how that imaging strategy works.

If the heads have already failed, imaging cannot start until they are replaced. Head swaps happen in-house on our clean bench with a donor matched to the drive, & the donor cost is quoted separately from the recovery fee. Single location, no franchises, nothing shipped out to another lab.

The checks in the triage section map onto those tiers directly, which is the practical reason to run them before anything else touches the drive.

Rush service: +$100 rush fee to move to the front of the queue. Donor drives are matching drives used for parts. Typical donor cost: $50–$150 for common drives, $200–$400 for rare or high-capacity models. We source the cheapest compatible donor available. There is no diagnostic fee, the quote is firm before work starts, & no data means no recovery fee.