I am using HL-DT-ST DVDRRW GSA-H21L ATA DVD rom. It worked well before i installed windows. but after i installed windows it cannot read cd disks. but it reads dvd disks. What can i do?
I think more information is needed, I guess you are talking about Windows 7 and it might just be that it is not compatible with this Drive.
The operative system installation can be a mere coincidence.
DVD burners have 2 separate lasers for CD and DVD media. If the drive shows problems only with CD discs, is possible that the CD laser is damaged, but being the DVD laser still working the drive can still be used with DVD media.
Do you have problems with [B]all[/B] CD media or only with burned discs? Can you boot the machine from a CD disc? You can do a quick test with any Live CD Linux distro
Welcome to the forum!
Bit of a coincidence that the drive would stop reading CDs after an OS reinstall.
Is there any other software installed that would interfere with drive operation - maybe burning programs like Nero (specifically the InCD portion), Roxio (inc. Drag 2 Disc) etc, or virtual drive/emulation software like Alcohol, MagicISO, or Daemon Tools etc?
Geno’s boot disc suggestion is a good one, it would rule in or out any software/OS problems.