No wifi connections are available on my laptop all of a sudden?

Okay, this can be fixed, but as I do not know the core of the problem, I'll give a few solutions for multiple situations.

First you can try to see if your computer has any hotkey to disable WiFi. Check your keyboard for a function key [FN] and a key with a WiFi symbol or something simular on it. On my laptop it is [F9]. If there is, try using that hotkey to see if your computer will find WiFi.

Another reason could be that your WiFi adapter is disabled. Go to your Control Panel, then System and then Machinery Manager, or you can search for Tool Manager. Look low the category for WiFi, if there is a unfit device right-click it and enable. If there is any device with an exclamation carve next to it or another icon that stands for non-working then attempt to right-click and uninstall and past restart your personal computer. If that doesn't work you could also right-click and search for updates.

Whether all that fails, then maybe your BIOS is configured not to enable WiFi. Restart your computer, and once the screen with the laptop or PC's manufacturer shows up with some text at the bottom saying what to press to go to the BIOS configuration, press those keys. Normally its [F2], but it may also be [F11] [F12] [F1] or [F3]. Then if one of the categories of the BIOS configuration shows an option to enable WiFi, make sure it is set to enable on beginning. Save and exit, and it will restart.

If all this fails, then I'd advice you to contact your laptop's manufacturer, or even better, the manufacturer of the WiFi device inside your computer.

Hope it helped!

Here are some google links to try if you want to, they might have some useful information:
http://www.google.nl/search?q=wifi+adapt…
http://www.google.nl/search?q=windows+7+…
http://www.google.nl/search?q=windows+7+…