no heat

Hi, help please
ok so I have this stack washer/dryer and the dryer stopped heating.
I did some troubleshooting as follows: tested the power/outlet and its fine, have 220 (110 x 2 where the dryer plugs in)
The dryer timer works (ticks off time) just fine in both the "auto" and "timed" modes and there is no heat in either the low or high temperature settings.
The air blows through just fine as does the drum turn just fine.
So I guess I need to know what is proper access to test the various element(s) thermostat(s)/sensor(s), which to check etc. and if there is or is not a simple "reset"

ty for your time friends C