I had power going to a switch and a plug out let but I had to change them out once I did they are both on two differnet breakers . Once they where changed I turned the power back on and the breakers instantly blew so I replaced them with new ones and turned the power back on and got nothing out of the switch or outlet so I checked with a multimeter at both and got no reading so I checked it at the breakers in the box and got no reading there so now half of my house is out of power when it was all working what could be causeing the problem and how can I fix it so I have power again please help fast I have children and need the power

OK, personally I'm going to need you to re-write that so folks can understand you. There's only one period in that whole thing.

Okay, lets see if I understand your questions.

You had a switch (what kind of switch, what did it control and why did you "have to change it") on one branch circuit.

You had a receptacle (what kind, why was it changed) on a different branch circuit.

Now, you set the breakers back to on and both breakers immediately trip?

Then you change something and now you have lost one of entire phase bars?

If you need this "fast"....call an electrician.