Multimeter time.
Set it to DC voltage and starting at the battery work thru the system until you don't get voltage.
Lights should come on even if the battery is low (they may be dimly lit), so I presume there is a break in the circuit somewhere.
Assuming the battery charge took (ie: battery isn't totally shot which is unlikely but check it first) and no 12v items work, my first guess would be a connection to the battery is loose or disconnected. After that try pulling fuses to see if they are burnt out (check the voltage across the fuse terminals when they are removed also).