how to fix my dvd rom drive to read the discs contents ?

First, check that the DVD drive is correctly connected.

Turn off the computer and UNPLUG it's power supply. The green LED on the motherboard must be off.

Open the computer case, un-plug and replug the power cable of the DVD drive and none other.
Next, do the same with the data cable: Un-plug and replug it from both the drive AND the mother board. If it's an flat ribon ATA cable, you don't need to touch the eventual connection for another drive.

You can now plug the computer and power it up.

If it still don't recognise a DVD, BUT recognise a CD, the lense may be dirty. Use some canned compressed air and blow it into the drive.
If it don't work, the lense may be very slightly missaligned. You don't have the tools, equipment and knowlege to fix that. You need a specialised technician. It may cost more than the price of a new drive.

If it can't even read an ordinary CD, it probably meant that it's dead and need to be replaced.

Electro
June 2011