This sounds like you may be in trouble for something. As a parent, it's pretty hard to convince me to give my son back his Xbox if he's grounded from it, however, there are a few things he could do to help me change my mind.
If he helps around the house, without being told. I like to see him being responsible and helping to pick up after others. When he plays with his brothers and sisters it makes me happy. If he comes to me and apologizes for whatever he did that made me ground him and explains why he did or didn't do it and what he's going to do to change that, I may also give in.
Really, it's going to depend on how your dad is. My dad was the type who said if I'm not getting it back for a week, no matter what I would do, I was not going to get it back!
Be nice, offer to help around the house, play with your siblings, babysit your siblings - put your mind to it and you might be able to convince him to let you have it back. Once you have it back, try to keep helping out or showing your appreciation and maybe next time it won't be taken away for so long!
First. Depends on your " error" done. But with us as parents. We always have sat down with our boys and try to reasons why we choose punishment as they say but then we ask them if we are wrong what punishment they feel they should get and for them to learn the error. End with a hug and kiss and don't do again. If possible. Coz we r human. Grt luck