Q: Home Button Stuck!?

My home button on my iPod Touch 4th Gen, 8GB stopped working this morning, I was using it fine the day before and was perfectly functional, and now it seems to be stuck and I quickly need a solution. I've been thinking about getting Apple Care but still am not sure. I think I have had this iPod for a while now but i can't find my warranty information. I shall be finding it out soon, What can i do to get my button back working? Is it clogged up with dirt? I already have Assistive Touch turned on. I'm finding it difficult and my iPod is not the same. I'm afraid that the replacement or repair will cost to much, and i don't want to replace it as i will lose all my music, contacts, apps, and app store money. How much would it cost to get a repair? As i said it was perfectly functional yesterday and i don't tend to press the button hard, but lightly. It's been going a little weird for a while though. As if i tried to get off an app and I would have to press the  button multiple times. What can i do to solve my issue? I have no idea what to do with it? :'( I'm also struggling to get my tough case off it! But i don't know if that's a problem as it worked fine yesterday with it on! I need to find a solution quickly so can somebody please help me out by giving me some advice, I would appreciate it. This is the gen i have.