Electrical Problem with 2008 Pontiac G6 (help please)

Headlights are probably a relay issue (relays are typically under your hood in an electrical panel). Tail lights and rear directionals are more likely either a fuse in your main fuse panel or a cut cable that leads to them. Check fuses first and, if OK, take a volt meter to one of the bulb sockets and see if you measure 12V from socket to ground when you turn on the lights. If you have power, the problem is either the bulbs or the sockets. Look closely for corrosion or rust (signs that a car has been flooded in water at some point in its life).

My daughter's had headlights, on her Pontiac G6] that repeatedly cut out. Problem was a connector closest to the headlamp that when connected both ends barely touched each other instead of having both ends of the connection overlap. When the connection got warm it would push itself apart and then cool and now there would be a space between connector blade and pinch spring. I "fixed" the problem by twisting the connector flat blade 40 or so degrees from the flat original position and this forces the connection to stay connected. Poor design you engineers. That is why people go to Toyota.