DVD Drive

Hello,
Sir,
my name is srujan,

i have one critical problem please solve this problem

First i can put a cd in the dvd/rw then cd works success but after some time a big sound from dvd/rw. i quickly open dvd/rw and then the working cd is cut in no of peaces in dvd/rw .
After i open dvd dome and clean dvd inner surface and set the dome fixing with nuts and then i put another cd . the another cd does not work and that can display please insert the disc.

this is matter so what is the problem?

and what is the solution please tell me sir