|if the reader head is damage then usually this is a job for a professional to replace, but can be expensive. also if the platter, motor, actuator are damaged its again a job for a professional.|
however what usually find is that the controller board on the hard drive is damaged, either due to over heating or possibly from a power surge.
these power boards are pretty inexpensive, around £30 and very easy to replace, but you need to ensure you get the exact same make, model. i have used this company many times and have always been given a working board
an excellent supplier, very helpful and usually able to provide you boards that you cannot find on their site.
no harm in giving it a try i guess if your data is worth it.