It sounds like you have the one outlet working which is being fed from the panel. The other two are likely hooked in parallel with the one working. You will likely find that the other two are not getting power because of a missing or unattached wire or two. You need to take the two receptacles which are not working out from the box they are mounted to in the wall. Be absolutely certain that the breaker controlling this outlet is off. If you don't know which breaker turns it off, I would suggest getting a circuit tracer to find out. Check for power before pulling the receptacles from their boxes. When you have made sure there is no power at the receptacles you have removed, you need to check the wiring which is either at the back or sides of the receptacles. Black wires should be going to the brass coloured screws and white wires to the lighter silver coloured screws. They may be pressed into the back of the receptacle. If you don't see a loose or disconnected wire, take the whole receptacle off and replace it. Do not use the press in connections at the back, wire the receptacles as above under the screws provided. You may have 2 or 3 of each coloured wire in any one box. You should also have a bare copper wire bonded to the box and a screw on the bottom side of the receptacle. If you are lost by now, don't do it yourself, get an electrician. Basically you need to see that the wires from the panel-fed receptacle are continued without interruption to the other receptacles. You will not likely have one receptacle fed by one breaker, usually more like 3 or even 6 or 8. If these are in bedrooms, you should buy arc-fault receptacles which are more expensive but to code. They are a little trickier to install though.
There are a few ways the receptacles could be connected and you need to see how this has been done. You also have to watch to see if they are split receptacles or not. The more I type this, the more I think I am only confusing you. You can buy a special tester that plugs into a receptacle and tells you if you have a neutral off or a ground fault or a hot wire off etc. You could start with that. But ultimately you need to have a tester and test for power and/or continuity and for proper wiring of all the receptacles. It could be as simple as a loose wire on one receptacle or more complicated like a fried receptacle. I would replace all the receptacles and wire them under the screws as opposed to into the backs....You must - again - watch for split receptacles - where you have two power feeds, and you have to watch for complete circuits as well as proper bonding of the receptacle to the box.
Hope I didn't confuse you too much.