Welcome to the forum
Has it stopped recognising both blank/burned discs, pressed DVD discs, or both? Any chance you can try the drive in another PC?
You don't say what OS you're using...if your version of Windows comes on DVD, like Vista, any chance you can try booting from that?
If your OS is XP or earlier, then my first suggestion still stands (unless you can get someone to burn you a bootable Linux DVD distro or something, to try).