|You don't give much info. Which firewall, doesn't sound like the Windows one, that lets pretty much everything through!|
If you are using the Windows one, open the firewall dialog box, via control panel, click the advanced tab and at the bottom, click 'Restore Defaults'
To help with another firewall you need to tell us which one you use.
Computers... designed to entertain,help with work but most of all to frustrate you!