I was installing a new Rite Temp digital thermostat to replace my old, but still working Weathertron. I connected all of wires properly, even tested it before I permanently mounted it to the wall and the A/C and furnace blower fan worked fine. Apparently, as I was attempting to push the excess wiring back into the wall durng the process of permanently mounting to the wall, I must have touched a wire with my screw driver or touched two wires together somehow or something and caused some type of electrical short circuit as now the A/C and blower fan no longer will come on... and the same results even when I reinstalled the old Weathertron. Is there a relay or fuse that I might have blown to have caused this that I can replace, or could the problem be more serious?

Thanks...

Hopefully, there is a low voltage fuse at the indoor unit that has failed. Otherwise, you may have overloaded and burned the transformer. Turn off power and have a peep inside the indoor unit.