cannot read d drive

[reariasq]

My computer will not read any discs in the d drive, which
is the cd, dvd rom, and cdr all in one. It will eject the
disc when you tell it to, and the light blinks on the
drive, but it will not read any discs, not even the system
restore discs.
I have an emachine with windows xp on it. Pentium 3
processor. 30 g hard drive. I tried to do a system
restore to an earlier date, but it will not work either.
Please help. I am scared to do a format incase it will
not read the disc to restore from after that. Everything
else works fine.
thanks