Troubleshooting Internet connection problems can be a challenge because there are so many possible causes. First, try these steps:
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 wires are connected (for example, make sure your modem is connected to a working phone jack or cable connection, either directly or through a router).
3. Reset your modem and router. Remove the power cord from the modem and/or router, wait at least 10 seconds, and then plug the modem and/or router back in.
4. Check your router. Because of the new networking features in Windows Vista, some older network routers are not fully compatible with Windows Vista and can cause problems.