everything worked but then...

Yea me and my brother played age of empiters for like a week (after school) and aol would work. But then one day age of empires doesnt show the games on my computer or it doesnt show the ping of my bros computer or nothing and on my computer when i dial up, and i want to go on aol it automaticly says that connection cannot be establiched. On my bros computer it works, but he is using a proxy server (which is my computer) to access the net. tcpip works good all my settings are good, i dont know what could of happened.