If not, your wireless card may be physically failing. Consider replacing it (for laptops, a $15 USB Wi-Fi dongle is the easiest fix).
If all else fails, bypass Wi-Fi temporarily to get online. install wifi driver windows 7
After following these steps:
Have a question about a specific wireless card? Drop a comment below with the Hardware ID, and I’ll help track down the driver. If not, your wireless card may be physically failing