If you've tried several (backup) superblocks and got the same error(s), basically you can probably consider the filesystem (at least) as dead.
The physical disk itself may or may not be. I tend to move them to my test box when I don't trust them anymore - some last for ages, some never come good, and get thrown in the bin.
Forensic software may get some of the data back, depending on whether the disk itself is still usable. Takes a lot of time if you don't have a backup.