startup problem

Started up computer.Get black screen.Shut it off with the power switch and restarted.SCANDISK stops @ 35%.Restarted computer with boot disk using Option @(without Cd-Rom support).Could not get to Windows.Error message:could not find drive E.Computerwas working fine till last night.
Specifications :
Custom built.256 RAM,20 Gb HD,DVD,CD-Rw,Zip nd floppy drives.Win 98.