I only know windows, but something similar happened to me recently. Linux distros could read anything, so I had to get some partition recovery software that I could run from the bootable OS drive. I haven't tried TestDisc,
Copy files from deleted FAT, exFAT, NTFS and ext2/ext3/ext4 partitions: http://www.cgsecurity.org/wiki/TestDisk
It can be a very big pain in the posterior trying to get something to give a good result after a scan as they pick up all kinds of partition boot records that have ever been formatted on the drive. Search for partition recovery software, and file recovery software. One of the best I used was called Active Partition Recovery. It takes some experience, by just installing and using these tools. After a while - 1 hour or so - I got comfortable using them. Just do not try to intialize or reformat anything, which you probably already know! Any DOS or live CD tools might write to the lost drive, so beware of that. Always make sure you save any reports to the correct drive that has your bootable OS or data partitions on it.
Active Part. Rec. was really good for this, and I think you can even make an image of your drive, even if it shows as RAW, for back-ups!
I did lose my data partition and the located files on it were not good enough quality to recover. I did get another partition recovered, though.
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