Use the Win 7 "Diagnose and Repair" function and see if that helps. If not, use the network to access your router and check to see if there are any firewalls or security measures active preventing you from connecting. Try resetting your router (i.e. power it down and power it back up 90 seconds later).
If the problem is with Windows itself, I cannot help you. Although I am running Win 7 HP as my operating system, I do not know enough about it for advanced trouble shooting.