Macbook pro does not connect wifi
before we go on fixing lets find out it is working at all.

In Terminal type (to turn it on)

networksetup -setairportpower en0 on


Next type (to scan)

/System/Library/PrivateFrameworks/Apple80211.framework/Versions/A/Resources/airport scan


Finally type (to connect)

networksetup -setairportnetwork en0 WIFI_SSID_I_WANT_TO_JOIN WIFI_PASSWORD


Also:

While holding the alt key click on the wifi icon

In the pop up window select Open Wireless Diagnostics...follow the instructions.