[John Rogers]

A little more info would help:
- what OS and version?
- What formatting is on the drive?
- When did this occur?
- Has it happened once or twice before becoming permanent?
- Has the computer crashed or stopped or froze in the last few days?
- Did you try to startup in Windows Safe Mode?
- Do you do an external backup?

Please let us know. Include a picture of your cat/dog so when we answer with the possible bad news it will not be so hard.