Laptop not recognizing any networks

For the past week, my computer wouldnt connect to a wifi network and my computer would crash. The only way I figured out a way to fix this was to create a new user account, which was working for a little bit. But a few times my Internet would crash and my computer would freeze. Now, my laptop won't even recognize networks, if I'm 4 feet from my wifi router. I have restarted my laptop numerous times, taken out the battery, and not used it for a day, nothing will make the networks come on again. Not one is showing, I have clicked on all the troubleshoot things and it cannot find the problem. It's not just mine because I can't do it at friends houses either. My Itouch and sister's laptop are both connecting to the Internet fine. Please help?