can i play any dvd cd in my cd rom/cd writer
if i install any software of it.saying it can play all the cd's???
if yes then which software can do this???

unless you made a typo ,[cd rom/cd writer]it need to read DVD/CD-RW.]you don't have a dvd player installed in you computer ,so you will not be able to play dvds'
If it was a typo and you do have a dvd player install .,you could get ,WinDVD player , or CyberLinks ,Power DVD .
If you bought the player new it should have come with software .

its obvious that they can be played in dvd roms.....

Your question is not very obvious, though. Are you asking whether you can play a DVD in a CD or CDRW drive?

If that's your question, the answer's no. Otherwise, I don't think anyone understands what you're asking.

Then it should also be obvisous that they can't be played in a CD Rom or a CD-RW !!!

The reason why you cant play dvd's in your cd rom drive is that the cd rom drive can only read cdfs file system while the file system of dvd rom is udf ... Yes you can play a cd in your dvd rom drive.