Car alarm will not turn off

I left my lights on. Came to the car the next day and realized it was the battery was not working. I then instantly bought a jumperbox but once I hooked it up my alarm turned on. Everytime I open the car door now the alarm turns on and that has never happened. The alarm is stopping my car engine from starting. How do I turn off my alarm sot that I can jump my car? Please help. I have done technics that I read online and none of them work.