I have replyed to another thread with almost the same problem as you.
I don't know why it happened, all i know is a way that might fix it.
I think that your Wireless network is no-longer automatically gaining the Internet protocol information, which has happened to me before, but not on windows seven.
To make sure thats its still working, go to network and sharing center.
click on adapter setting.
right click on wireless network and click properties while on an admin account.
click once on Internet protocol version 6.
at the bottom, there should be a properties option.
click it.
make sure that the cirles obtain ipv6 address automatically is checked for both boxes.
click ok and then click once on internet protocol verion 4.
click...