Install "Complete Internet Repair"... It will try to repair the active connection... after running it and rebooting, if it doesn't fix the connection..
go to the Device Manager Computer/right click and select Manage... Device Manager / Network Adapters / right click on the Ethernet device / select Uninstall.. next reboot the computer and allow time for a auto re-installation of the Ethernet adapter. If it doesn't install successfully, go to the Device Manager and install the driver manually.
If Complete Internet Repair doesn't repair the Wi-Fi connection, also try the manual adapter driver installation. You can find different driver installation tutorial/guides with complete instructions for manual installation.
How To Install Hardware Or Device Drivers Manually In Windows 7 / Vista
http://www.addictivetips.com/windows-tips/how-to-install-hardware-or-device-drivers-manually-in-windows-vista/
How to Install Drivers in Windows 7
http://ftp1.digi.com/support/images/Win7DriverInstall.pdf