My touch 4g was working fine the whole day. When I got home from school, I went to play on my xbox. Then i went to play music on my touch while playing but when I pressed the home button nothing happened. So I pressed the sleep/wake button and nothing happened, I even held it for a few seconds but nothing happened. After I plugged it in my computer and still nothing happened. What's wrong? If it's broken, I bought it off Amazon so where would I replace it? Also do all touches have warranties?