|Try using a laser lens cleaning CD in the drive. If you don't have one you SHOULD have one. Most places that sell CDs or DVDs sell them, and even some "dollar" stores have them for a buck or two.|
Or, if this is a laptop computer, eject the drive's tray and with no disk on the tray, wipe off the obvious laser lens with a tissue or a soft cloth.
If that doesn't help....
Are you SURE the drive can read DVDs ? - CD only drives cannot read DVDs..
All DVD drives can also read CDs.
Combo CD / DVD drives have at least two lasers and associated circuits. Sometimes one of those malfunctions after the drive has been used a lot. The only cure for that is to replace the drive.