Boot to the Installer disk, but do not Install.
Answer only the "what Language" question, if presented.
Wait a quarter minute for the MenuBar to be drawn.
Choose Disk Utility off the Utilities Menu.
Is you Hard Drive there?
--No, it may have died.
--Yes, Use Disk Utility to Repair or Erase it. If it has been troublesome, consider erase with ( Security Erase ) option Zero all data, one pass. If this completes without error, your drive has 100 percent good blocks again (spare blocks may be substituted for any that have gone bad). The process takes several hours.