How do I reset the auto defrost

Your refrigerator may have a mechanical defrost timer or it may have a electronic circuit borad.

IF your refrigerator has a mechanical defrost timer, as shown below, locate it.

It may be behind the toe kick in the compressor compartment it may be in the rear in the compressor compartment or it may be inside the refrigerator next to other controls.

Using a flat blade screwdriver, turn the center shaft clockwise about 1/4 turn. Note that it can be turned only one way. You should hear and feel the shaft clicking as you turn it.

If the compressor motor starts to run, the timer is defective and must be replaced. While turning it will restart the compressor it will almost surly stop again in the nest defrost cycle.

These type of defrost timers are generally generic and can be purchased at appliance parts stores like Tribble's. Take old one with you.