Diagnosis
A seized idler pulley or a broken drive belt. The motor hums because it's engaged but can't turn the obstructed drum.
How to Fix It
Unplug the dryer. Access the drum area by removing the front panel. Try to manually turn the drum—if it's very hard to turn, a roller or rear bearing has seized. More likely, inspect the drive belt. If it's snapped or slipped off the motor pulley, the drum won't spin. Replace a broken belt and check the idler pulley spins freely.
If That Didn't Work
The motor itself could be failing or have a bad start capacitor, but this is less common than a belt/pulley issue on this model.
Heads Up
Don't let the motor hum for more than a few seconds—it can overheat and burn out, turning a simple belt repair into a costly motor replacement.