Find or create a CD/DVD that can be used to boot a computer (test that it works in another computer).
Try to see if you can boot your computer using a bootable CD/DVD, e.g. your Windows install disc, in your Sony DW-G120A drive. You may have to change settings in your BIOS to allow booting from your DVD burner.
If your computer can boot from the bootable CD/DVD but can't read the same CD/DVD in Windows, then it's a software problem.
If your computer cannot boot from the bootable CD/DVD, then it's a hardware problem and you need to get a new drive.
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