My dog is out of control

My dog has always tried getting into the garbage or human food but it has gotten extreme and out of control. She will go through the trash right in front of me (used to wait till nobody was around) will eat any food she can reach, she tore open a pizza box today while I stepped away there wasn’t any food in it. She is 12 years old. I don’t know what to do and I don’t know why she’s doing it. It’s getting really bad. Help.