sounds like your dvd burner has died, heres a few things to check.
does it power on ? ie, does the eject button work ?
secondly, if it's a new pc, it's probably running a SATA dvd drive, & sata leads have a nasty habit of falling out.... unscrew the left hand side of the case & check the leads are all firmly in place.
also, if you get the latest ut04 game patch, you don't need the disc to play the game, just install the patch & it'll run just fine....