I had an MBR partitioned NTFS drive that was used on a Ubuntu system running my media server.
I snagged that drive (4TB WDC DM-SMR (PMR) USB) and tried to access it direct from my Windows 11 pc. It wouldn't mount, and I couldn't access it. In the standard Disk Management tool, it showed 2 partitions, both "unallocated", but using Linux Filesystem Browser software allowed me to navigate it (this wasn't ideal because it only let me "recover" files to another drive, vs directly access them.

I accidentally clicked "Convert to GPT" and it didn't prompt anything, it didn't "do" anything, it just changed from 2 "unallocated" partitions to a single one, and I was no longer able to view the files with any linux explorer programs, nor can I access the directory structure or files directly on a linux system either.

I don't believe that any formatting happened, so I think that the files should be mostly intact somewhere in there. What can I do??

This is what DMDE is showing. It's currently doing a full scan, and is indicating the presence of files.

https://preview.redd.it/li8br7bxqnfc1.png?width=967&format=png&auto=webp&s=c510717b1aab53a564b945a11d8fee0d55e4db80