Search guides

Fix a partition that is lost

We'll check Disk Management, use TestDisk to recover the partition table, and avoid actions that erase your data.

Troubleshooting · Home maintenance
30–90 min
What you'll need
  • TestDisk (from cgsecurity.org)
  • Administrator access
  • Another drive to copy recovered data to
  • Bootable USB (if the lost partition is the system drive)
Step 1 of 6

Quick triage — pick your path

Quick triage — pick your path

Choose the option that matches what you see. You can jump straight to that section.

Show full guide

Steps

Goal: Recover a lost partition without initializing or formatting, using TestDisk to restore the partition table.

  • Do not initialize or format the disk. Initialization erases the partition table and makes recovery much harder.
  • Good: You have not initialized. Proceed to Disk Management.

Do not initialize

Goal: Avoid actions that destroy recovery options.

  • Do not click “Initialize Disk” in Disk Management. Do not create a new partition or format. Any write to the disk can overwrite the partition table or data.
  • Good: Disk is untouched. Proceed to TestDisk.

Disk Management

Goal: Assess the current state of the disk.

  • Open Disk Management (diskmgmt.msc). Note whether the disk shows “Not Initialized” or space shows as unallocated. Note the disk number and size. If the lost partition is the system drive, you may need to boot from a USB to run TestDisk.
  • Good: You know the state. Proceed to TestDisk.

TestDisk

Goal: Use TestDisk to find and restore the lost partition.

  • Download TestDisk from cgsecurity.org. Run as Administrator. Select the disk. Choose partition table type (Intel for most). Run Analyse > Quick Search. When a partition is found, press P to list files and verify. If correct, select Write to save the partition table. Restart.
  • Good: Partition reappears in Disk Management and File Explorer. Copy data to another drive immediately. Bad: Quick Search found nothing—run Deeper Search.

When to get help

  • The disk makes clicking or grinding sounds—do not run recovery tools; contact a data recovery specialist.
  • TestDisk and file recovery software find nothing—a specialist may have better tools.
  • For RAID or complex setups, professional recovery is often needed.

Verification

  • The partition reappears in Disk Management and File Explorer.
  • You can open the partition and see your files.
  • Data has been copied to another drive.
  • No initialization or formatting was performed before recovery.

Escalation ladder

Work from the device outward. Stop when the problem is fixed.

  1. Do not initialize Avoid initialization and formatting—they erase the partition table.
  2. Disk Management Check diskmgmt.msc to see disk state (uninitialized, unallocated).
  3. TestDisk Run TestDisk to search for and restore lost partitions.
  4. Deeper Search Use TestDisk Deeper Search if Quick Search finds nothing.
  5. Recovery software or pro Try file recovery software or contact a data recovery specialist.

What to capture if you need help

Before calling support or posting for help, have these ready. It speeds everything up.

  • Disk number and size
  • Whether disk shows as Not Initialized or Unallocated
  • TestDisk results (partitions found or not)
  • Whether data was recovered

Does the partition show as unallocated or is the disk "Not Initialized"?

Disk Management shows the current state. Do not initialize.

Open diskmgmt.msc. Check the disk. Unallocated/Not Initialized: Do not initialize. Data may still exist. Good: You know the state. Bad: Partition visible—different problem.

Yes No, partition visible

You can change your answer later.

Have you initialized or formatted the disk?

Initialization erases the partition table. If you have not, recovery is possible.

If you have NOT initialized: good—proceed to TestDisk. If you HAVE initialized: recovery is harder but TestDisk Deeper Search may still find data. Good: Not initialized—run TestDisk. Bad: Initialized—try TestDisk Deeper Search or recovery software.

Yes, I did No

You can change your answer later.

Run TestDisk Quick Search

TestDisk can find and restore lost partition table entries.

Run TestDisk as Admin. Select disk. Choose partition table type (Intel). Analyse > Quick Search. When partition found, press P to list files. If correct, Write to save. Restart. Good: Partition reappears. Bad: Try Deeper Search.

Yes No

You can change your answer later.

Run TestDisk Deeper Search

Deeper Search scans the whole disk for partition signatures.

In TestDisk, run Deeper Search. Wait for scan. When partition found, verify with P. Write if correct. Good: Partition recovered. Bad: Try file recovery software (Recuva, EaseUS) or contact data recovery specialist.

Yes No

You can change your answer later.

Partition recovered

Copy all data to another drive immediately. Do not save back to the same disk. Verify files are readable.

Done

Contact data recovery specialist

If TestDisk and recovery software find nothing, or the disk makes clicking/grinding sounds, contact a data recovery specialist. Do not run more tools on a failing drive.

Done

Reviewed by Blackbox Atlas

Frequently asked questions

Why would a partition disappear?
Common causes: accidental deletion, partition table corruption, power loss during write, virus, or disk error. The data may still be on the disk—do not initialize or format.
Will initializing the disk recover my partition?
No. Initializing writes a new partition table and erases the old one. It makes recovery much harder. Do not initialize if you need the data.
What is TestDisk?
Free, open-source tool that scans a disk for lost partitions and can restore the partition table. Run from a bootable USB or another OS if the lost partition is the system drive.

Rate this guide

Was this helpful?

Continue to