Disk Drive not loading disks

I was recently given a mac g4 computer, and I cannot get it to read the disks in the drive, it doesnt even register that there is a disk in the drive. I have tried with CD's DVD's and Games and none will register. Any ideas what to do? any help would be appreciated.

Go to the Apple in the top right hand corner. open About this Mac, then open More info, in the list of contents check under Disc Burning to see if your BURNER is registered as operating? if its not an Apple dvd machine, you will need to install the driver for it, It could be a loose cable, or it could be that the drive is bad.
If you have a local Apple store they'll test it for you !.