My whirlpool dryer worked fine in the morning, then would not turn on. When I looked at the back of the dryer I noticed the light was still on in the dryer through the vent. I think it's not latching somewhere,but the door clicks when I shut it and is closed.

Open the door and locate the door switch. Operate the switch to see if you can get the light to turn on/off. If you can't then the switch may be bad.