Why does a dryer not heat & dry

Because its broke. Time to call the service guy or find out why the heating elements aren't heating if you have the right tools to test things.

Our Crystal ball is out for calibration so we can't be more specific.

If dryer runs but does not get hot the thermal fuse is probably blown. If the thermal fuse is blown the vent is probably obstructed or tube dirty inside. You can Google thermal fuse replacement for location but you have to take the back off tne fuse is on the air duct that carries the exhaust to your flex. Pipe. It has 2 wires and 1 screw usually white or off white.