Sounds like you lost one leg/phase temporarily.
May want to contact someone that knows what the hell they are doing, an electrician. I'd recommend opening up the main-panel and perform some regular maintenance, such as retorquing all lugs, all breakers and main incoming lugs. If you have a laser thermal temperature reader, look for higher temperatures on any of the lug connections. A lose connection will create resistance creating a higher temp or an overloaded circuit will create a higher temp as well and a thermal laser tester will identify it.
An open main panel while hot is very dangers to work on so, that is why I suggest you have someone that knows exactly what they are doing.
Good luck!