How to get over protective parents to trust there kids again?

My friend is 12 years old. Her parents gave her a lot of trust, but the rules they gave her, she didn't like them at all. Her mom always used to say she doesn't want her hanging out with guys & honestly that's not a big deal. She did it anyways, She went to the mall with a group of friends. & sometimes including her boyfriend. When they found out, they put her on lock down. They never let her hangout with friends again. Once they found a text message from him her mom slapped her & took her phone away for about a month even longer . Her mom is always complaining about how she never doesn't want to hangout with her because she always says mistakes she did in the past. The daughter gets annoyed so she doesn't like that. She feels like her parents her bad most of the time. She has sneaked out a couple of times just to have fun. Her parents found out cause her little brother told now they have cameras all around the house recording. Now all she wants to do if for her parents to trust her around guy friends, let her have her phone back even though she doesn't hangout with mom, let her go out with friends at age 12, about to be 13 alone.. . It's an age that she can't always be around her parents anymore. She's always depressed all the time now. Please help? :/