Key will not turn in ignition! Battery?

[nautiquelfe]

Hey guys i was out earlier this evening cleaning interior of car both doors were open and all interior lights were on. i didnt leave any lights on but when i went out some 3hours later my key will not turn in the ignition. The battery seemed to be very weak and the lights are dim. I am trying to charge battery w/ booster cables but am not having any luck, been on for approx. 30mins. Im not sure if it helps but the headlights will not turn on either, maybe the ignition has to be on for them to work. If it matters at all its a 99 model. Any clues or suggestions, i will be getting new battery for sure but i dont have radio code and nearest dealer is approx 60miles away. thanks for support in advance