I'm sorry to hear that, PM me with the following information and I'll try to help.
are you on lan, network, or directly connected to your modem?
what kind of internet 56k, dsl, cable?
how many people in the same house, can they connect?
when's the last time it worked?
did you change anything to your files? to play another server for example.
do you have a firewall?
do you have an antivirus?