If your computer is connected to a network, network policy settings might prevent you from completing these steps.
Network discovery is a network setting that affects whether your computer can see (find) other computers and devices on the network and whether other computers on the network can see your computer. By default, Windows Firewall blocks network discovery, but you can enable it.
Open Advanced sharing settings by clicking the Start button , and then clicking Control Panel. In the search box, type network, click Network and Sharing Center, and then, in the left pane, click Change advanced sharing settings.
Click Turn on network discovery, and then click Save changes.
If you're prompted for an administrator password or confirmation, type the password or provide confirmation.
For information about setting up a wireless network, see Setting up a wireless network in Windows 7.