I guess it would depend on what you mean by "unreadable". If it is mounted and you cannot access data at all then you are likely out of luck. You may try a 'dd' to wholesale copy the bytes on the disk to another good disk, but again, if it is 'unreadable' then by definition you cannot read data from it. In any event, from your physical description of the disk even a dd may well be the straw that breaks your HDD's back...
Have you had a look at SMART?
Might be a bit late for that now though.