Windows 7 - DVD rom will not read DVDs but will play cds.

Hi all was wondering if someone could help me, My DVD rom drive will not read dvds or dvd software but it will play cds, This has happened before to me but I was able to call someone, It happened after I Uninstalled Norton and I had to remove a key and restart the laptop up and it worked, But I cannot remember for the life of me on how to do it again, I Uninstalled Avg then reinstalled it since then my drive hasn't been playing dvds just cds. I know This is probably the same as what has happened before, I know I have to go into regedit but not sure where to go after that, Can someone please help me on getting this drive working again
Thanks In advance
OS windows 7, Home Premium x64

Have you tried going into device manager and deleting the DVD drive and then refresh and let Windows detect the drive.

Maybe the DVDs you are using are not compatible with the drive

Hi guys just wanted to say thank you for your help first off, I actually done a system restore to before I uninstalled avg and now the DVD is working fine, I am assuming it was what I suspected, and it was a key problem, thank you all for your help really appreciate it