is it possible to recover deleted files from a flash drive? (If so, how?)
A few years ago I recovered deleted photos from an SD Card using software I downloaded.. I honestly can't remember the name of the software but it's somewhere along the lines of Rescue Recover or something like that.
But yeah, I guess it's sort of possible.
Yes, it is possible if you did not write data on this flash drive after the deletion of the files. Otherwise, you may be able to get back all the deleted files.
If I remember well, I already followed this HowTo for Linux but it's available for Windows and Mac too: https://itsfoss.com/recover-deleted-files-linux/