Why is half of my house without power with no flipped breakers?
Well usually when "half" of something dies in residential electrical, it means one hot leg is down. This could be an issue at the transformer, the wiring to your meter, the meter itself, the wiring from the meter to your main panel, the main breaker or a fault within your panel. 

It is pretty easy to test for, you're just looking for 240v at the service entrance. If you get 240v there, the issue is downstream in your house wiring. If not then it's likely a utility issue.  Testing does however require testing live circuits. 

Since it doesn't sound like you have the experience to troubleshoot this safely, your best bet is to contact a qualified electrician.   It might be necessary to then contact the utility depending on the outcome.