There are a few things you can do which would give you a reasonable idea about the nature of the hard disk problem.

Logical problem if there is something wrong with the boot sector of the hard drive rendering it un-bootable.

* Boot from a floppy and do a read only scan of the disk. You will be able to decide on an appropriate strategy for fixing the master boot record. If the boot sector is lost then you should be able to decide how to go about recovering the data. If there are bad sectors in the master boot record, then attach the hard drive to another working computer as a secondary hard drive and try to recover data using software hard drive recovery.

Electrical problem where the circuit board on the hard disk has been damaged due to a higher than allowed electrical current passing through it.

* Open up your system's ATX cabinet box, take out your hard drive, and closely examine the circuit board under the hard drive. Do not touch the board as static discharge can damage the disk's head. If there are telltale signs of a burnt circuit board or burnt components, then you can decide for sure that it is a board problem.

Mechanical problem where the head that reads the data stored on the different platters arranged inside hard drive damage or the alignment of the platters themselves affected.

* The sure sign of a mechanical problem is the clicking sound that you will hear from the hard drive when it is trying to spin up or spin down. If this click sound is coming, then the problem related to mechanical trouble inside the hard disk platter assembly.

Data recovery protection with reasonable degree of success is perfectly possible from a damaged hard disk or other kind of storage media. As long as you have access to internet, so the best policy is to backup the important data on your hard drive so that, you are not left with the costly and time consuming option of data recovery in case of damage to storage media.