Dear Daming,
I'm very sorry to hear that your parents got back the mobile phone from you. I guess you must be very sad with it. but I think your parents just hope you can pay more attention to your study.
as a student, You can try to use the mobile in a proper way, we can use it for calling and send message when you need to contact or be contacted by your friends or your family.
It is not wrong to use the mobile to listen to the music or chat, while the time should be limited or you will waste a lot time on the useless issue. you can try to communicate with your parents to get it back, and spend less time on the message and listen to music. I am sure your parents will understand your situation and get your mobile phone back.
I