how can i fix a problem on my imessage?

how do i fix my ipod i cant login to my imessager account on my ipod4 its up to date on ios 6.1.6 but it wont let me log in i put my info in and it takes me to the next page then asks me if i want to use my email and i hit next then it will say verifying and it takes me back to the login page and i try it again 6-7 more times but it wont let me get past the verifying page it keeps taking me back to login screen what do i do and i know my account works because i still can login to my other ipod???? what do i do?? and i cant delete the acount from the ipod because it wont let me on??