Grandma throwing an anger tantrum

This is my first time posting here, but I'll keep it short. Sometimes I like to fix phones or laptops as a favor for people and I usually don't charge them, but they give me money anyways because they think I'm a kid and all.

My grandma told her friend about me and he decided to give me an iPhone 4S to unlock. I didn't think anything of it until I noticed it was stolen and the original owner locked it and had a number to reach him. I wanted to contact the original owner and do the right thing, but I didn't think it was my place, so I told my grandpa to call the guy up and tell him I don't work with stolen things and to come pick it up.

Fast forward a month later and the guy never came to pick it up. I left the phone in a cabinet on our computer desk and told my grandparents to give it to him before I went to school in the morning. It's been there ever since and I just noticed it was gone earlier today while I was searching for something. My grandma is now threatening to kick me out of the house unless I find the phone and she's throwing a huge tantrum over the whole thing. She cares more about what people think about her than her own grandson it seems.

Any advice as to how to approach the situation?

Lol what the actual heck

If it was stolen, then you should have turned the phone into the carrier (at any store) last month, and they would locate the owner and contact them.

Find out whether your grandma took the phone somewhere and then forgot where she put it. Has she gotten any calls or visits from the guy who brought you the phone to unlock, or from the original owner himself? Did she give it to whoever asked for it, and now doesn't want to admit it? Tell her it was "hot property".

Ask around in the family, poke around in the computer desk, look on the floor and in nearby places, and try to find that phone. Did you save the number that can make it ring? If you find it, take it to a store that carries and services that brand, and tell them the whole story.