OK to be more specific go to CONTROL PANEL then to NETWOK AND SHARING CENTER then to NETWORK CONNECTIONS. FIRST!!!!!!!! Make sure the device in enabled (right click on the ethernet connection then click ENABLE if it is not an option then move on). At this point you should see your two connections, one being Ethernet and one being wireless. open the ethernet one... click once on the Internet Protocol 4 and then click on properties. Make sure the "obtain IP automaticlay" is checked. (this is assuming you use DHCP on your router or let the router set its self up i.e. using the CD it comes with) then save or click apply/ ok.
If it still doesn't work then try to update your NIC card soooo.....
Do the same as above BUT DONT click on the Internet Protocol 4 just click the Configure button,
then click on the driver tab then update driver... (you will need to connect to the internet for this so your your wireless) then click search automatically.... and who-la one of these two should fix your problem IF NOT THEN you can leave a post here or leave a message for me and I will help you out further.