The upstairs of my house consists of two rooms that are powered by two 20 amp breakers which are tied together. A few days ago one of the rooms lost all power while the other room continues to work fine. The power is still out and I have reset the breaker several times and this doesn't work. Could one of the 20 amp breakers be bad? Or, does it sound like there might be another problem. Would turning off the main breaker help? Thanks in advance!

If those 2 breakers are for 120 volts, remove the tie, unless you have some special system needing connection to both disconnected at the same time. It is possible to turn only half of a 2 pole breaker, turn all the way off, then both sides all the way on.

If the wires connected to the two breakers (black and red) go to a 3-wire cable, you have two circuits sharing a common neutral (white). The reason the handles or the breakers are tied together is to insure that both circuits are off should you be working in the box where these two circuits split off. If the breaker did not trip off or does not trip when reset, chances are that you have an open connection in the circuit that does not work.

Turn off both breakers. Remove one of the outlets that does not work from its box. If the outlet is wired by inserting wires into the little holes in the back, chances are that is you problem. This type of wiring is known to develop bad connections over time. Remove the wires from the back and put under the screws on the side. If rewiring all the outlets does not fix the problem, check the switches, this type of wiring can be used at a switch to pass a hot wire connection through the box. Still no fix, check the working outlets. Sometimes the bad connection can be in the outgoing wire. The outlet works, but the current is not passed to the next outlet. Check hots and neutrals. An open neutral will also cause failure.
What the heck, you might as well rewire all of your outlets and be done with it, if you don't it will happen again in a year or two.

HEROLD - I agree fully, nice answer ::: F.B.E.

HK is correct, it used to be tied if it was 2 circuits were on one duplex receptacle with tab broke. Haven't seen in practice though.
HK tried to give a green, wouldn't allow. Still I Agree.