First, there should be a fuse under both under the dash and the hood. check them, but honestly, since the problem has come and gone, chances are the fuse isn't the problem. My first thought is a bad main switch on the driver's door. Check it to make sure it is getting power. It should have 12 volts all the time and only actuate the lock solenoid when the button is pushed. If there is 12 volts to it, make sure power is coming out of the switch when you push the button. If it isn't replace the switch.
Here is a how to for checking the actual locking solenoids. Again, I doubt they all went bad at the same time, but it does offer the directions for removal and checking.
remove the driver's side electric lock switch and see it there is power to it and when actuated, if power comes out.