I do not mean to be flip or insulting here, but this has happened to us, so please take it in that spirit. Note: I am assuming that you have no power even with the generator running, if you have power with the generator and not with the electric plugged into shore, than disregard the Easy Button .
The EASY Button: I don't know which ACE model you have, but my 2015 has a power disconnect on the side of the steps as you enter. My grands were occasionally toggling it when they came in or out of the RV and stopped on the steps to put on/off shoes. If this was accidentally pushed into the off position it would explain why no power. And you wouldn't know it had been pushed, which is why I now keep mine taped in the on position.
The not so EASY Button: Otherwise you have to deal with RV hide and seek--looking for fuses and connections related to the converter box at the battery and at the converter box. It could as simple as a fuse to the converter, a loose connection to the converter, or you might need that multimeter. I have not had to deal with this one. Yet.
Hope it was the Easy Button solution.