You have lost one leg of the voltage going to the heater filaments.

A fuse protecting the heater element opened.

The heating element stretched/sagged and contacted metal which caused a short.

That's the best I can do given that you gave no information.

Gas or electric dryer? Roper Dryer Troubleshooting, Manuals & Repair by FixYa Could be what Don says if electric. If gas it could be the thermostat or the high heat protection link