My alienware 14 does not detect my dvd rom most of the times, it detects it once out of 20 restarts.

Hi Tjprog,

If you feel comfortable opening the computer, I recommend re-seating the optical drive. Check your Owner's Manual for disassemble instructions. 

Opening the computer means losing the warranty, am i right?

can't i just get an engineer to come home and fix it.

Check out this video and follow the troubleshooting steps, let us know if this helps you fixing the issue without disassembling the system. 

if re-sitting the dvd rom was the problem, then the system should not detect the drive occasionally, 

but i tried following the steps in the video some weeks back, it crashed my operating system (windows 7) i had to upgrade to windows 8.

can't i just get an enginner at my place to sort this, or your office address, i am located in Nigeria.

Regards

In that case you will need to contact the technical support site in your country so they can help you with the replacement.