Belt has borken - Dryers

Remove the top cover by removing the screws at the back of the machine and sliding the cover off forwards. Now you need to obtain access to the complete circumference of the drum to fit the belt. Depending on your machine you can either remove the front of the dryer, or release the rear bearing support so that you can slide the new belt over the drum and under the bearing retainer, which may entail removing the back cover as well. The belt then just slips over the motor pulley and you need to check on the belt tension, usually done by adjusting the motor or the tensioner.

How to open a cabinet:

http://www.partselect.com/dryer+open-cabinet+repair.htm

belt diagrams:

http://forum.appliancepartspros.com/dryer-repair/25860-dryer-belt-diagrams.html