reiserfs file system failed under checking. now cant be accessed

[OErjan]

Oh, never said it was solved, just told you to BACKUP! reason being the rebuilding can actually make damage WORSE if it is physical, if there dust or similar on the disk it will make the head jump and create more damage when it hits the face...

uhm, just to let you know, I have had disks less than one year old in stationary low load backup-server (say 2 hours/day) standing in climate controlled room (temp, humidity...) die from physical failure, I dare not think how easy it would be to damage an external drive, just moving it while spinning can do this and as some can still spin quite a while (1min+) after they are disconnected...
There are quite a few things that can go wrong with any filesystem, journaling ones like Reiser, EXT3... are better but far from failsafe.
is there a second journal somewhere else on the disk that you can try rebuilding from? there should be.