Run a few virus scans and anti-malware tools. If that doesn't fix the problem, try starting up into safe mode and then using the disk drive. If the disk drive works in safe mode then it is most likely due to corrupt windows files, the easiest fix for this would be to run a repair install of windows 7.
Hopefully this has helped you, please get back to me with your results.
Safe mode won't fix corrupted Windows files but it can prevent other drivers from loading that could interfere with the optical drive. Did you remove anything related to disc burning or CD/DVD/Blu-ray playback recently?