Sorry, I should say why I am asking the question.
It sounds to me as though your CD drive mechanism has become un-plugged internally (for it not to be seen) - it is very easy to accidently pull the plug off the CD drive when you open the back of the B2 and pull the tray out a smidgen too far!
If this has happened it is not serious and either way I would recommend that you check the plug is fitted properly.
To do this, disconnect the B2 from the power and remove the top two screws holding the back plate onto the B2 (they are marked in the case with a little ">" mark.
Pull the rear panel away form the back by about 4 cm (1.25 inches) and if you now look underneath the boar that comes out, between the board and the base of the case, slightly right of the centre, you will see some wires coming from the board to a
little PCB board. On the front of this boar is a plug that fits into the rear of the CD mechanism.
You may find that you PCB is floating free, if so with your fingers gently orientate the board so that its back edge is parallel to the back of the B2, and push it forward until it finds and seats into the CD mechanism's socket and gently but firmly
push it into place.
Push the back panel back into place and replace the screws. You can now test the B2 to see if it sees the CD drive.
Fred