To resolve the issue of not receiving files on ICQ after reinstalling it, users should check their firewall settings and router configurations. It's essential to ensure that the firewall allows traffic through the ports used by ICQ, typically between 1080 and 1802. If a firewall is in use, users need to enable both incoming and outgoing access for the specific port ICQ is using, preferably selecting a port above 1023. If behind a router, enabling port forwarding for the chosen port to the local machine is necessary, often involving Network Address Translation (NAT). Users should avoid placing their computer in the DMZ due to security risks. In ICQ's preferences, users should adjust the Firewall IP settings, with options to use internal, automatic, or external IPs, and configure TCP listen ports for incoming events to a range above 1023. If issues persist, further configuration of the broadband modem may be required.