I had a sudden DVD/CD failure - replaced drive but windows would not recognise - followed process below, I am no expert but maybe worth a try as it worked.
Find DVD CD rom drives
scan for hardware changes
Insert CD into drives
See if recognised
If not next step depends if you had case off when your mate was helping you.
If you did I would disconnect drive, check if sharing IDE cable, if so make sure one set to master one set to slave using jumpers on back of drive - reboot.
Reconnect - reboot
Try above again
If you didn't have case off if that fails then my limited experience has run out - maybe faulty drive like I had ?