Download this tool and tell it to do a scan, it will fix network problems and conflicts. http://iobit.com/AdvancedWindowsCarePersonal/index.html
If that doesn't work, go to start run and type services.msc make sure that the services with network, wireless and dhcp are all started. then try to connect.
If that doesn't work go to start then run and type cmd when it comes up, type
ipconfig /release press enter
ipconfig /renew press enter
ipconfig /flushdns press enter
Once you have done all this try and connect If that still doesn't work, go to your network adaptors, right click the one that you are trying to use, select properties scroll down the list until you find internet protocol tcp/ip select that and go to properties. make sure it is set to recieve ip address automatically.
Hope this helps