No such thing as 220v or 230v, only 240v; which some people insist on
calling almost anything. However, you are thinking of 208v, which is two
legs of three phase; but since you don't have 3 phase, it really doesn't
matter.

Check out:
http://www.networkcable.com/pages/co...onlocking.html
It will tell you what voltage your outlet is supposed to be. (though I have
no idea why they call it 250v!)

I am guessing you have a 6-20, but it could also be a 5-20.
If it is a 6-20, it sounds like one half your your breaker tripped, though
that isn't supposed to happen. If it is a 5-20, then perhaps you have a bad
neutral connection somewhere.
Did you try resetting all the breakers?