Not recognising

Hi
Ive just had my computer upgraded by a friend and he has changed from pentium 4, to a dual core system - im not too good at these things. I kept my Benq DW400 a burner in, but the problem is it used to be a E drive, but now its not installed and the computer cant find it. When i turn on the unit i can open and close it but as soon as windows comes up on the screen during boot up, it wont open or work. Is there any ideas> thx
Greg