Check setup (F2) to make sure the hard drive is still detected. If it isn't, replace the CMOS battery and try resetting it. If it's still not detected, chances are your hard drive has failed.

Thank you for the information.  I also noticed that the lights on the back of my computer are lit up with 3 green and then 1 yellow.  Do you know what this means?  Any information is so much appreciated.

Most likely that your hard drive is dead. Try reseating the cables to the drive and going back into BIOS seutp. If the drive still is not recognized, replace it - it's dead.

What causes it to die?  Thanks