What to do right now
- Do not convert the disk back, initialise it or create new partitions.
- Check in Disk Management whether the partition is missing, shown as RAW, or only lacks a drive letter.
- Search the whole physical disk for lost partitions and save the files to a different disk.
Step by step
Stop converting
Converting back to undo the change writes yet another partition table, and the tools built into Windows only convert an empty disk, which means deleting volumes again. Leave the disk as it is now.
Look at what Disk Management shows
If the partition is still listed with the right size and file system but has no letter, right-click it and choose Change Drive Letter and Paths. That only assigns a letter and does not write into the partition. If it shows Unallocated or RAW, continue with the next steps.
If the PC no longer boots after mbr2gpt
A system disk converted to GPT needs UEFI boot. Switch the firmware setting from Legacy or CSM to UEFI, usually in the BIOS setup. The data is normally intact; do not reinstall Windows to fix the boot problem.
Run FileFix Ultimate from another drive
Use the portable version on a USB stick, or the rescue USB if Windows will not start, and run it as administrator. In Deleted file recovery, select the converted disk as a whole physical disk.
Check the partitions it finds
The app reads the current MBR or GPT and searches the disk for partitions that are not in it, using boot sectors and the NTFS backup boot sector. Compare each candidate's size and file system with what the disk used to hold, then run the Balanced scan on the matching ones.
Copy the files to a different disk
Save to another physical disk. Once your files are safe, you can rebuild the partition layout with a partitioning tool or set the disk up fresh.
Why files seem to vanish after a conversion
There are three common routes. Disk Management and diskpart can only convert a disk with no volumes on it, so the option stays greyed out until every volume is deleted. Many people follow a tutorial, delete the volumes, convert and only then realise what was lost. In that case the conversion is not the cause; the deleted volumes are, and they are usually recoverable as lost partitions.
The second route is mbr2gpt, which converts a Windows system disk in place. It validates the disk first and changes nothing if validation fails. When it succeeds the data stays, but the PC may not boot until the firmware is switched to UEFI, which can look like data loss. The third route is a third-party converter that was interrupted, for example by a power cut, and left a table that no longer matches the partitions on the disk.
Disks that look broken but are not
An MBR table can only describe about 2 TB of a disk with 512-byte sectors. On a larger disk, space beyond that limit shows as Unallocated, and converting to fix it is a common reason for experiments that go wrong.
Some USB enclosures present the disk with 4096-byte sectors. If you take the disk out and connect it directly, the partition table appears to point to the wrong places and the disk looks empty or RAW. Some enclosures also encrypt the disk. In both cases, put the disk back into its original enclosure before you convert or scan anything.
What a conversion writes
Converting to GPT writes a protective MBR and a GPT header with its partition entries at the start of the disk, and a backup copy in the last sectors. Converting to MBR writes a new MBR at sector zero. These are small areas, so partitions that started at the usual 1 MB position keep their boot sectors and files. That is why searching the disk usually works, provided nothing was formatted or installed afterwards.
When it won't work
- After deleting the volumes and converting, new partitions were created and formatted and files were copied onto them.
- Windows was installed onto the converted disk, which overwrites large areas.
- The disk is an SSD and TRIM erased the space when the volumes were deleted.
- The disk was encrypted by its USB enclosure and is now connected without it.
- The partitions used ReFS or APFS, which are not analysed.
How FileFix Ultimate helps
- Reads both MBR and GPT layouts and searches the physical disk for partitions missing from the current table.
- Recognises NTFS, FAT32, exFAT, ext4 and HFS+ partitions and uses the NTFS backup boot sector to confirm where a partition ended.
- Never writes a partition table or boot sector, so it cannot make a failed conversion worse.
- The rescue USB lets you copy files off a PC that stopped booting after a conversion.
- Free for personal use, with no recovery limit and nothing uploaded.
FileFix Ultimate is free for personal use, works offline and never writes to the drive you are recovering from. Business use needs a one-year licence per PC. Check the signature before you run it.
Frequently asked questions
Does converting MBR to GPT delete my data?
mbr2gpt and many third-party tools are designed to convert without deleting data. The converters built into Disk Management and diskpart work only on an empty disk, so the data loss comes from deleting the volumes beforehand.
Should I convert back to MBR to get the partitions back?
No. Converting back writes another partition table, and Windows will again ask you to delete volumes. Recover the files first; the old layout can be rebuilt afterwards if you still need it.
mbr2gpt failed with a validation error. Is my disk damaged?
Usually not. When validation fails, mbr2gpt stops before writing anything. Common reasons are too many partitions or no room for the EFI system partition. Your data should be as it was before you ran the command.
The partition is back but shows as RAW. What now?
The partition entry exists but the file system cannot be read. Do not format it when Windows asks. Scan it in Deleted file recovery, which can still read damaged NTFS, FAT32 and exFAT structures or find files by signature.