Do everything your mom likes you to do without being asked. Be really sweet and give her reasons to want to give it back to you. You have to be a good kiss up to do this and at the end off all that if she still hasnt given it back or mentioned sit down with her and tell her you need it for school.
If she took it because you did something bad than don't ask it.The consequence will double if not triple!!Wait a few more days than maybe bring it up in a polite and innocent way.Don't argue just bring the subject up!Good luck!ps.you'll survive without it trust me!!haha :)
Why would you get grounded for asking to get back hour iPod? Just ask her. Nicely of course. There's nothing wrong with it and I'm sure you're mom would understand. It might make you an Indian giver but not a rotten kid