when you connect to the wifi can you see any of the devices connected to the wifi in your network? if not then you might not actually be connected to the wifi...
here are some basic troubleshooting steps to try...
1) connect the pc directly to the router via a lan cable. make sure you can access the net from the pc at all.
2) when connected wireless, right click on the wireless icon in the taskbar, select "open network and sharing options" then on the right hand side of the screen select "manage wireless networks", then remove your home network from the list of wireless networks. then try to reconnect.
3) double check the router's setup, when connected via a lan cable to the router, type 192.168.0.1 (typically, sometimes it will be 192.168.1.0, if neither of those work, hit your windows key, type cmd into the search bar, and then ipconfig in the command prompt, the "default gateway" is the address you need to type into the internet browser. checkout the wireless setup in the router. make sure you're using the right password, double check the router does not have a static ip (typically static ip wireless routers are limited to 10-20 devices that can connect... ever... or at least until you reset the router. if it is static, then a router reboot is probably needed to clear out the "other devices"). make sure the router isn't set up to only allow certain MAC addresses to connect... and double check to make sure there aren't any ip address conflicts (this is typically a problem with static ip routers; though it also can happen if you have a wireless hub configured improperly attached to the network).
4) if you can't determine that anything is wrong... try a reboot of the router. unplug it... wait a minute then plug it back in.