To troubleshoot a network connection problem, try these steps first:
1: Open Network Diagnostics by right-clicking the network icon in the notification area, and then clicking Diagnose and repair.
2: Make sure that all cables are properly connected.
3: If you're trying to connect to another computer, make sure that computer is on and that you have enabled file and printer sharing on your network. For more information, see Networking home computers running different versions of Windows.
4: If the problem began after you installed new software, check your connection settings to see if they have been changed.
To check connection settings
5: Test your router to see whether it is fully compatible with Windows Vista by running the Internet Connectivity Evaluation Tool.
If these steps don't solve the problem, look for a specific problem in the following table.