Ipod touch problem!? :(?

My Ipod Touch has been acting weird for the last couple of hours and then all the sudden it stopped me from going on any apps or update any apps, so i though it would turn it off and turn it back on again... but now, as ive pressed the "slide to power off" button, the screen is just black with the loading star thingy in the middle (you know, when your internet is loading symbol). it has been there for now two hours and still hasn't seemed to turn off yet.

I have plugged it into the computer but no reaction? what shall i do?

Thanks to anyone that can help :)