it is optical type of secondary storage which is used to hold media data. well depends on what you want to do if you want to just burn dvds or open dvds but if i were you try to find one that has both
A DVD ROM is a "Read only Memory*" it is the disk itself and as such it cannot burn anything.
A DVD reader can only read DVDs.
A DVD writer can write som recordable DVD formats.
It could be that the writing lens is dirty. You can try a DVD drive cleaning kit.If a simple cleaning does not help then the software and or drivers for the DVD drive may not be working correctly....