Ipod wont turn back on

Hello,
i did not have apps onto my ipod touch so i could not download games, so i decided to upgrade my ipod of itunes which i have bought. when the upgrading was nearly finished it came upo with an error and now my ipod has turned opff and has an image of an apple as though it is doing something but it wont turn on or when i plug it into the computer it is not coming up as it is connected to the computer and wont come up on itunes. If anyone has any information that would help me i would be really greatful as i would like to get the ipod working soon as possible thanks.