hey askolhe,
I assume that there are no breakers 'tripped' at the panel. It sounds as if you have a break in the 'supply' to lights. What would be required is examine the connections in the lightswitch boxes and the boxes at the lights. What you are looking for is the first feed in from the panel that is not correct. I am guessing that power is fed to the light fixture and not the switch in which case in the electrical box at one of the lights you will find a connection has come loose and needs to be repaired. The supply will come into this first box and split off to that rooms light switch and also go over to the next rooms light fixture.
Do you know what an 'Non-Contact AC voltage detector' is? Do you have one? By using one you can check for a current without opening connections for a multimeter to touch
In this diagram if the supply coming into junction box A is disconnected then that light as well as other fixtures past it, ie fixture B, will not work.
I have made some assumuptions for this problem and your house may be wired a little different... like the supply going to the light switch first, patience and careful examinations will help you solve this one. I hope this helps, Jim