*Could* easily be as simple as a GFCI recept. has tripped. 50 or 30 amp service? If 50 amp, might be one supply leg is out. If 30, you may have a little more digging to do.
Yes, get a voltmeter. Take cover off panel and check voltage on load side of each breaker. If this all checks okay, I'd say it's a 99.9% probability you have a bad connection at a receptacle. You might even turn each breaker off and back on in case one has tripped and you can't see it (the handle only moves part way).
If you have a whole whack of receptacles out suddenly and at the same time, I'm guessing you have a tripped breaker or GFCI. Breakers do fail once in a while, but that's pretty rare. It's also possible you have a wire that has come off at the rear of the receptacle, but that should be the last thing you might check for. Found a bad one in our own trailer.
Worst case scenario: If you find a tripped breaker or GFCI and resetting it restores power, but it trips again right away, then you could have a real problem to fix because you have a have short circuit somewhere. Or you have a leakage to ground somewhere. If it's been raining a lot, it's possible that some water got into a recept. somewhere and tripped a GFCI. If that's the case, you'll have to investigate for water intrusion near the receptacles.
Gil & Deb & Dougal the Springer Spaniel