It could be a number of things, if you can hear the motor humming and it starts to turn if you push the drum it could be the motor capacitor.
If there is no noise from the motor then either of the timers may have failed, there is a reversing timer hidden in the base of the machine as well as the one you use to set the drying times which does give this fault. It could even be a faulty motor but that is not common.
Bear in mind that if it has been left in a drying cycle without the motor running for more than a few minutes then the heater safety cut out ( stat ) will almost certainly have gone as well.
Circuit and component testing with the mains plug removed using a megger or suitable multimeter is the only way forward.
That which can be asserted without evidence, can be dismissed without evidence.