Wi Fi A networks are 5 GHz, Wi Fi B networks are 2.4 GHz, Wi Fi G networks are 2.4 GHz, and Wi Fi N uses both 2.4 and 5 GHz bands.What this means is that if you have a 2.4 GHz wireless NIC (which is the most common), it will not work on an A network.
Find "Internet Protocol Version 4 (TCP/IPv4)", click it, and then click "Properties." Then click "Obtain and IP address automatically". Find your network adapter and right click it, click properties, go to "Internet Protocol (TCP/IP)" and click "Properties". If you want to obtain your DNS servers automatically, you can change those as well.If your router is an A router, then you need to get a wireless NIC that supports 2.4 and 5 GHz networks.If your computer connects to other wireless networks, and you have verified that you have the correct frequencies, then more than likely it is not a hardware issue. I have been involved with sound and lighting since I was 7 yrs old.
I currently do Information Technology work for a living, and professional sound as a side job. Due to a recent demand for help with home networks, I have decided to write this instructable on how to troubleshoot your home network.
You can try checking the drivers to make sure there are no issues or updates, but if it isn't a driver issue, I strongly suggest just buying a new wireless NIC.