Good looks like a relatively new load center.. you need at the minimum a two lead circuit tester (has a little xenon bulb in it)
As you lost power throughout an entire circuit, you either lost a breaker or there is still a GFCI hidden someone you missed.
You need to eliminate the circuit breaker first and start working out from there.. (as you have already figured out that there is no power at the outlets)
The wire that is screwed to each breaker is the wire that goes OUT to the outlets.. one lead of tester goes on that wire and the other can go to any white or bare ground wire... if it is a bad breaker, one of the black wires is going to be dead..
If you find that all the leads are live and you can not find the GFCI, you are going to need more help than a forum I think..