First Use HDDlife to find Life of ur Hard drive, if its satisfactory then use any partition manager and try and solve ur problem.
If the life is unsatisfactory then better go for the new one bcoz Formatting ur hard drive again will do no good to ur Life of ur Hard drive
and worsen the situation
scandisk only detects and marks ur bad sectors............. which means those paarticular sectors are discarded and are not used for reading/writing in future. the recovery options tries to copy the data present in those bad sectors to healthy sectors. scandisk won't remove the bad sectors. even formatting doesn't help much(i've heard that a low level format helps to some extent but i am not sure how to go round)........... bad sector is a bad sector and a disk with bad sectors is not reliable. time to get a new disk..........