I have a 1TB Seagate External HDD (STEA1000400), that on a whim I decided to optimize/defragment on my laptop (I'd done it on desktop before). I realize now that was a dumb idea since the USB ports on said laptop can be unreliable; the drive had apparently shut off during the "consolidating" portion of optimization.
Upon trying to use it again the drive was inaccessible. I initially tried running the normal "scan drive for errors" but it appeared to freeze. chkdsk returned the drive format is RAW. In checking this I also couldn't properly eject the drive and the laptop wouldn't shutdown on it's own, so I eventually just unplugged it again (which hopefully didn't make it worse – nothing was being done to the drive at the time AFAIK).
From what I've looked up so far, I believe the best course of action is to make a backup image of the drive and then run testdisk on it. But I'm currently a bit overwhelmed by the options, so if possible I'd really appreciate some feedback/guidance regarding the particular situation I'm in.