Exactly what Speedy Jim said. Seen it in a friend's barn/garage once,
where it was a 240V pump in the position where your oven is.
You can verify that you're missing one of your two hot legs by looking
at the position of your breakers in the box. Reading down one side,
you're going to have working - not working - working - not working, and
on the other side, just the opposite. (Assuming you've got all single
pole breakers. If you've got the little half-sized ones, it'll be two
working, two not working, etc. And double breakers getting 240V aren't
going to be working either.)
I agree, call the power company and ask them to check your service. If
you're lucky, it's their problem.
WARNING: some of what I'm suggesting below is potentially DANGEROUS.
If in doubt, hire a pro. Depending on your locality, you may have to
hire a pro anyway. Where I live, I can do this work on my own home,
but your locality may not allow it.
If the utility company says that everything checks out to the meter,
you may be able to diagnose it and fix it. A voltage tester (one of
the pens that lights up is sufficient, but do test it on a few known
good and bad outlets first, so you know what hot and not hot looks
like) should allow you to trace your service from the meter through the
breaker box and figure out where one of your two hots stops being hot.
Even if you throw the main breaker in the breaker box, some parts
(usually the top area near where the wires enter from the meter) are
hot anyway. Be careful where you touch.
You should be able to find two lines coming into the breaker box that
are hot. If not, you've got a problem between the breaker box and the
meter. If you've got two hots into the breaker box but half the black
wires coming out of your breakers aren't testing hot, suspect the main
breaker up at the top of the box. If you're lucky, you have a shutoff
out on the meter box, and then a separate panel inside, so you could
shut power off at the meter, put in a new main breaker, and then turn
power back on at the meter. If your meter doesn't have a shutoff that
will cut power to the entire breaker box (not just all the breakers,
but EVERYTHING), you'll need the utility company to come and disconnect
your service while you fix the problem.