My dryer makes a thumping noise every time the drum rotates can you tell me what causes that?

The thumping noise your dryer is making is caused by worn out drum support rollers. They are little rubber wheels that the back of the dryer drum rides on when its running and when the rubber or bearing on the wheels get bad it will causes the drum to make a thud sound each time it rotates. Just have the drum supports replaced and that will stop the noise.