Hi Cindy and Dale,
I would start troubleshooting by going on the roof and spin the fan by hand. Make sure it spins freely. If not, inspect for something like a twig to even something wound around the shaft of the fan, check for clearance between the blade and everything else.
If the blade spins freely, then you can look into the next possibility. Maybe the switch that turns the fan on/off when opening and closing the cap has malfunctioned. I am not sure where that switch is located in our fan. If you can get to it, make sure it is aligned right and clicks on/off when the cap opens and closes. Maybe the switch is good but got loose and is not
There is no need to go on the roof. Just pop the screen off from inside, like when cleaning the fan/screen. You can do everything from inside. Ron must have one of the old style fans that required removing a bunch of screws to remove the screen.