The power windows on my '78 just stopped working this morning. I put them up in the morning, parked the car, then 8 hours later, when I started the car again, the windows (both of them) no longer would come down. Any ideas on a possible cause?

 

Since it's both that quit working, check the fuse.

 

Theres a relay under the center consol, if you can make the windows go up & down with a jumper wire than the relay died.