cd/dvd drive failure (i think)

i have an inspiron 6400 with an hl dt st dvd -+rw gsa t11n drive. lately the drive is not being detected at the my computer screen..on opening the device manager, there s a yellow exclamation mark there. i also have an optiplex desktop which faced the same problem a couple of weeks back. over there i re-installed XP..while re-installin there came an error sayin ASMS file is missin.. then thru the net i had to tweak the registry files n then i could re-install the entire XP.. but re-installin XP on my laptop is out of the question. i nhave too much in this to lose. anyone of you all has a bright idea to solve this mess?? thanx n waitin for ur replies...