When you should call your computer professional.

1. Strange Noises
2. Full Hard Drive
3. Blue Screen of Death(Windows)
4. Light for Drive always on or flashing
5. Slow startups and slow operation

Data recoveries can cost thousands of dollars.

Another tip with a drive that has failed is to remove the hard drive from the computer and place in plastic bag and put in freezer for 20-30 min, just long enough for it to get cold. 9 out of 10 times it will work.