Chevrolet Repair: key wont turn, graphite powder, lock cylinder

Question
I have a 1995 Camaro with a dead battery I have not turned on in about 2 months. I used my girlfriends car to jump it, and the lights in the car come on, but I can't turn my key. I bought graphite powder and I still cant get it to start. I bought a new ignition cylinder or whatever it's called from the dealership about a year ago. I've tried turning the steering wheel, I made sure the car is in park, I'm not sure what else it could be. Any ideas?

Answer
HI ALEX, YOU BOUGHT A NEW LOCK CYLINDER,YOU DID NOT SAY IF YOU INSTALLED IT OR NOT ??? I WILL ASSUME YOU INSTALLED THE NEW LOCK CYLINDER WITH KEYS ??? HAVE YOU TRIED A DIFFERENT KEY ??? IF NOT TRY IT SEE IF THIS HELPS.. NEXT STEP IF THE NEW KEY DOES NOT HELP, YOU WILL NEED TO PULL THE LOCK CYLINDER OUT OF THE COLUMN AND SEE IF THE LOCK CYLINDER ITSELF IS THE PROBLEM OR IF IT IS IN THE COLUMN..ONCE THE CYLINDER IS OUT SEE IF THE KEY TURNS THE LOCK.IF IT WILL NOT,,, TIME FOR ANOTHER LOCK CYLINDER,IF IT DOES TURN THEN SOMETING INSIDE THE COLUMN IS JAMMED.COULD BE THE ACTUATOR GEARS OR THE IGN SWITCH VERY RARE HOWEVER..I DO NOT KNOW IF YOU HAVE EVER REMOVED THE UPPER HALF OF A COLUMN BEFORE OR NOT  ?? IF YOU NEVER HAVE THIS MAYBE SOMETHING YOU WOULD LIKE TO TAKE TO A REPAIR SHOP..BUT FIRST LETS FIND OUT WHAT IS LOCKED UP AND GET BACK TO ME..GOOD LUCK TOM..