Out of nowhere this afternoon a few light in the house stopped working... we're tried shutting the breaker and turning it back on and we turned off the main power switch and turned it back on... it's not the bulbs what could it be and what should we do next??

Start at the panel and determine which breaker handles this circuit. Make sure you have power coming out of the breaker by testing for 120 across the black and to a white. If power leaves the breaker and is not reaching inside the socket it could be a loose black or white wire at the first socket in a sting of sockets. If you have a ground wire at the first socket and there is no power between black and white then test black to ground. If this shows power but the other way did not then you lost your ground. Do some testing and come back with the results