Can't connect to xbox live...?

i connect to live usually through a wireless router, however lately it has not been able to receive the ip address, it is set to 'automatic' to find it, and it shows it has one, however i don't know what to do. i have internet, which is the annoying thing, cuz i now know nothing of what to do... i have tried turing everything off and on, but i just can't seem to get it to work... and ideas?