Are you saying you have 110 volt power showing at receptacles but if you plug something in it won't turn on? That makes no sense. Please provide more details of your test readings and specify what won't turn on. Usually the type of problem you describe has nothing to do with faulty equipment, but with a GFCI receptacle tripping somewhere.

Without knowing what you mean by your meter and tester 'showing power', this is my guess:

There is a loose connection somewhere.

When you said that you replaced "all outlets, switch and breakers" I'm assuming that you just replaced the devices that didn't work? And the breaker that controls that circuit?

Then the loose connection is probably some other outlet that is on that circuit that is working properly but a connection in that box that is feeding the non-working outlets is the problem.

Or as kudzu said, there's a GFCI outlet somewhere that's tripped.

A digital multimeter is the wrong tool to use for home electrical testing. Its high input impedance causes it to read voltage ("phantom voltage") where no useful current is available.

Something like this is what you need.

Also, randomly changing receptacles, switches, and breakers isn't a practical solution to a problem like this. It's a waste of time and money, and it seldom fixes things. Would you keep going to a mechanic who did that with your car? I sure wouldn't, and don't.

You need to do some detailed troubleshooting to determine where the defect really lies. This requires a basic understanding of how electrical circuits work. If you don't have the electrical theory background, I strongly recommend that you call in someone who does.

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