Like others suggested, I would try to reinstall your network drivers. If that doesn't work, I would just buy an external usb wifi card. They are a cheap and easy solution, which could offer better performance depending on the wifi chip that came preinstalled on your laptop.
My usb adapter did that one time as well. Unplugging it and plugging it back in seemed to resolve the issue. Now, while this is much more complicated to do for laptops, I would try to open it up and check the connection to your card. (I would only do this if have some prior experience with computers and networking.)