This should be a pretty easy question to answer. A whole-home power outage is difficult to miss, even if it happens during the day. The sump pump may stop working if there’s a power outage because it needs to have power to pump the water out.
Many sump pumps have backup power, but if this power option has failed without you noticing, the power outage may have caused your pump to stop. Though it can be frustrating, it’s also not the end of the world.
If the whole home has lost power, don’t worry too much about the sump pump. Wait until power comes back on to the rest of the house, then come back to see whether the sump pump is working. If it’s still not working, that’s when you may need to contact a JES expert to see what’s wrong.