Have you tried clearing cache/history/cookies? Do you have any proxies enabled on the browser? Have you tried restarting the computer? In short we need a few more details of what you've tried and what you haven't if you don't know how to do what I've listed here I'll explain but I need to know what you've done to try and troubleshoot this. Please post back.
Try disabling and enabling again the connection (Control Panel -> Network and Internet -> Network Sharing Center -> Manage Connections, select your connection and disable it, then enable again). That helps me when it decides not to work and none of the Diagnose and Repair stuff works.
I had a similar problem...you could try using a different browser such as Opera(google for it and download it). I'm somewhat sure that your registry files haven't been affected yet...so try this:there are softwares out there such as “Explorer Repair” that resets your TCP/IP settings, deletes ARP Cache, repair your host files, checks your winsock files. This could solve the problem or try uninstalling internet explorer and re-installing it.