b. Hard drive is NOT recognised and grinds/scratches/clicks. As in (a) above, but there is nothing the user can do without a full drive rebuild - seek specialist help.

c. PC powers but error message “cannot load operating system” or similar. Assuming there is not a problem with the computer itself (eg PSU), this suggests the boot sector is damaged. To recover the data, use specific data recovery software to repair the damage, or seek specialist help.

d. Hard Drive is NOT getting power. Almost certainly a PCB fault, but be aware this is often coupled with (a) above. Try swapping PCB (ONLY with identical part number, firmware revision and PCB number). If the user then experiences (a) above, disconnect power immediately.

e. Hard drive is vibrating. A very common problem with drives manufactured in China - the spindle bearings are seized. This will require a full a full strip down and at best, re-lubrication or at worst, bearings/spindle/motor replacement.

f. Hard drive is slow to respond/irregular crashes. Assuming that you have already cleaned up any unwanted processes or applications, scanned your disk for infections, de-fragmented, adjusted virtual memory etc its time to suspect drive failure. Back up data and run SMART test to determine drive performance – if in doubt, replace hard drive.

g. Data is garbled when opened or will not open from thumbnails. Probably logical problem from an infection, or bad sectors effecting specific files. Use specific file repair utility for that type of file extension.

When diagnosing hard drive problems, the rule is NOT to take any intrusive actions. This includes running CHKDSK, writing more files to the hard drive, using the internet etc. If you are going to run a disk utility, use software that takes an image .img of the hard disk surface before starting the repair/recovery process.

Reference: http://www.datarecoveryspecialists.co.uk/blog/typical-data-loss-scenarios