How can I get my phone back?

if I want to persuade my mom to get my phone back nicely without pissing her off and having a high chance of getting it back can you tell me?
I got my phone taken from the teacher for listening to Marilyn Manson in-betweenclasses which I have been doing for a number of days now the last time a teacher caught my phone which was forme listening to Pink Floyd and then she sent it to my mom and I told her that all I was doing was listening to music but she still refused to give my phone back to me. The gym teacher who took my phone away today was even being an asshole about it so he gave me a warning and said put your phone away right so i already had my Bluetooth headphones connected to it so without him knowing I tried to turn it off by going to the settings but I must have been acting really shady and he walked over to me and interrogated me and then told me I was lying and said a story which sounded believable but it wasn't true so then he took my phone and said "we'll see if your mom will come pick it up" which she will, but im starting to think that she will take it away because o fbad grades from me getting depressed.