Roper dryers
are the same as a Kenmore or a Whirlpool Brand,
when the dryer is not heating you would want to check a few things in this order.
1. Is the dryer getting enough power?
2. Is the dryer gas or electric?
OK, so you are getting enough power to the dryer ( 110v to gas dryers) (110v to apartment size dryers) (220v to normal size dryer) then lets check;
2.the cycle thermostats ( located on the heater can) test for continuity )
3.the timer