Why isn't my Wifi turning on or connecting?

My WiFi will work for a minute or two after a restart, then stop OR the computer will not see any network hardware. I've tried resetting the PRAM and replacing the airport card. The same thing is still happening. After the Wifi drops, if I try to turn it off, the computer will say it's off in System Preferences and will not turn it back on, but the desktop toolbar icon at the top will say it's still on and connected. Trying to turn the WiFi off via the desktop toolbar does not turn it back on either even though the icon will say it's connected. The ethernet does work. A friend recommended reinstalling the OS which I have not tried yet but I was wondering if there's another solution.

Macbook Pro 13" Late 2011

Running El Capitan