are you sure they are not on a light switch?

it could be any number of reasons from a loose conneciton to bad wiring to tripped breaker/GFCI. the only way to tell is to start troubleshooting from one to the other.

Kitchens and bathrooms are where one would typically find a GFI. If these rooms are bedrooms or other living space, you might be chasing a ghost.

A wall switch that controls one receptacle (or half of one receptacle) in a room is pretty common (but you may have already checked that). Without knowing the layout of your home it's pretty hard to say if they would be on the same circuit or different circuits.

Is there any evidence that the previous homeowner may have been a DIY electrician. People do the strangest stuff that makes perfect sense to them but to no one else.

How did you determine that these receptacles aren't working? A lamp (for example) will not light if either 1) there is no power coming into the receptacle or 2) there is a bad neutral. Knowing where the problem lies may help you find a solution.

There's no evidence that the past owner was a DIY'er, I'd say the opposite.

Of the three outlets that aren't working, one is halfway up a staircase, one is in a bedroom and one is in an a section of the attic. The only common things between them that I know of is that they're on the same side of the house...

In the bedroom there is a wall switch that controls half of a receptacle, but that's a different outlet.

I determined they weren't working by plugging a couple of different things into them to see if they worked... Things I knew worked because they were fine in other outlets.

So what I'm looking for is suggestions on how exactly to troubleshoot? Is there some sort of outlet tester that will tell me if it's a bad neutral, or whether the outlet is even live? Will some gadget tell me if it is a GFI somewhere?

I'm just not sure the steps I should go through to narrow down the cause... I know they dont work, I've tried finding a gfi somewhere, what's next?

I going take a guess that they are all on the same circuit. Start at the one closest to the panel and open it up and measure for voltage. If there is none then try and determine which other device might be on the same circuit and start checking them.
The problem could be in a working device.
The first thing I would try is one of the three light plug in testers and see what it tells you.

Have you checked all your breakers? They may not looked tripped but sometime you need to turn them off then back on to reset them. Hopefully the panel is marked so you can tell which breaker controls these receptacles.

You keep saying you've checked for GFCIs, but have you checked for tripped breakers?

I'd pick a time when there's nothing important going on in the house and cycle them ALL off then back on, just to be sure. All breakers that I know of have a "tripped" position (usually half way between on/off) but it's not always far enough away from ON to be immediately or easily visible. One would think a half-way-on breaker would stand out noticeably in a panel full of all-the-way-on ones, but that's not always the case.

Come on guy's-Let's read the OP question FULLY-
The OP stated:
I thought it may be a GFCI outlet somewhere, but I've searched everyone and the only ones I can find aren't the problem. I've also tried flicking off/on every circuit in the breaker box.
Why do we keep telling him to check the breakers? He already stated he flipped them all off and back on!

steve_fl, relax. I've been posting to this forum since the beginning 2003, with very few errors - I think I'm entitled to mis-read a line once in a while!

Geez

pharkus-
this was not a slam against you or anybody else (I personally have used your advice on several occasions)-
It just seems that in looking at many of the posts lately, they get off topic very quickly, or the OP has given information in the post that is not referenced by the people who are offering advice, and they tell him/her to do again what has already been tried.
In this case, out of 4 replies to the OP's question, 3 of them told him to "turn the breakers off and back on".

Once again, not a slam against all the expert advice given so graciously (and free), but an observation to assist the OP get their problem solved.
Sorry if any of you took this the wong way!

Problem solved!

After wasting a bunch more time trying to figure out where/how these outlets were all connected and what else they might be connected to I finally found another GFCI outlet. I feel kind of silly, the number of times I'd seen posts along the lines of "you wont believe where I found a GFCI" had me looking *everywhere* (at least I thought so) to try to avoid doing the same.

Anyway, turns out the GFCI was in a small closet in the hallway outside a bathroom. There's clothes hanging in the closet, so I couldn't see it (halfway up the wall). It doesn't really seem to make much sense how its wired up... The three outlets in question are spread right along one side of the house, this GFCI is in the middle of the house. But whatever, it works now!

Thanks heaps for the replies everyone :)