Is there an FCC Requirement that requires that you physically be able to turn off the wireless router in our laptops? The reason I ask is because for novices or any non-technical computer user, that little switch will cause many headaches. If you can't connect your laptop to a wireless router or if your laptop suddenly doesn't work on the Internet, there is a good chance that you have found this switch. Look around on the front of the laptop or side (they usually put it in a really convenient spot to entice accidents), and flip that switch and watch your Internet come back on. If that is indeed the problem, you will see a light right next to said switch come on. This light is green, blue or orange generally (I only have four laptops and they are all one of these three colors ;))
Other possible solutions may be that you have the software turned off on your operating system, though this is generally not the problem, since the pain "suddenly" started (and you were looking at the screen when it cut off).
What do I check if this did not fix it? I would check your router and modem (cable/dsl) or your combined router/modem. Note: If your unit is combined, smash it with a baseball bat and go buy something else (joke). Otherwise, you want to unplug BOTH units for 30 seconds and plug them back in (I usually do them in synch, but believe it is recommended to turn the modem on first).
Note to self: If you ever design a switch like this, put it in a spot so that everyone knows where it is and make it harder to accidentally switch (like, it should break long fingernails).