It sounds like your heating element has gone out. You probably need to call a repairman and explain what it is doing. If the drum is turning, then I can almost bet on it that it is the heating element.
Most likely the lint trap for your dryer needs to be cleaned. If it is blocked, air cannot properly vent, which would keep your clothing from drying. It is also possible that you are trying to dry too big a load.
The most likely problem is the volume of clothes is too large. Try limiting bulky items such as towels to one or two per load. Also, a full lint trap may limit the effectiveness of the dryer, so make sure you empty it before every load.