Steps
Check to make sure your computer is on and is connected to a network.
Be aware that Windows has a built in function to repair a network connection. This function can give valuable information in the form of an error message if you know what you are looking for. Some common error messages given are:
Unable to clear the DNS cache
Unable to renew your IP address
Unable to clear the ARP cache
Deal with a message that states "Unable to clear the DNS cache." When you get the message ?Unable to clear the DNS cache?, this usually means that the DNS client service has been disabled. Follow these steps as an administrator to re-enable it:
Open the Services MMC plugin, located under Administrative Tools in the Control Panel;
Find the ?DNS Client? service in the list presented and enter it's properties by double-clicking it;
Change the Startup Type from Disabled to Manual or Automatic then click apply;
Either reboot or click ?Start? to start the service;
Verify by attempting to repair the connection again.
Fix a problem related to an IP address. If the repair process reports that it has been 'Unable to obtain an IP address', it is probable that more information can be obtained through the command line. Open a Command Prompt by going to Start > Programs > Accessories > Command Prompt, then type 'ipconfig /renew' to attempt to obtain an IP address from the command line.
Follow up the error messages that will likely appear. There is a high likelihood of an error message similar to the one below occurring, the remainder of the guide will foc