My HP notebook does not play DVD's. - Computers & Internet

Does it play CDs perfectly fine ?
Did you check with other good (branded) DVDs ?
If possible, remove this dvd-drive, connect it with another laptop, and check.

If problem started after you installed anything, try undoing it through System Restore (All Programs - Accessories - System Restore).

Boot the computer in safe mode (tap F1 or F11, select Safe Mode), log in as Administrator.
Check if it reads DVDs here or not.
Create a new user account (Control Panel - User Accounts). Restart computer normally, and log in using this new account. Now check if DVDs work or not.

If still not working, backup your important data (write on blank CDs, or copy in USB pen drives), and then format the hard drive. (Restart the computer, and tap F10 to initiate recovery from hard drive partition.)

You may also use the Recovery Disk you got with this notebook. (Insert disk 1 in the drive, and restart the computer, and just follow the instructions).

If still no progress, chances are the DVD-drive lens has gone for a toss. Buy a new dvd-drive.

Hope this solution helps you.