Ipod touch frozen. Help please

Ok. I dont exactly know if its actually frozen or not, but a week ago, i jailbroke my ipod and it worked perfectly. Then two days lter, my brother put a passcode on it to be funny, then he lock my ipod to the limit until the apple startup screen showed up. I thought everything would be deleted which i dont mind, but now, everytime I turn on my ipod, the screen appears and the loading thing appears and then the circular loading screen just freezes and then it shuts itself off. I cant do jack with it and iTunes does not recognize the ipod when I plug it in. Help please.

Whats DFU? Im new to this stuff.