Wi-Fi can’t be turned on (MacBook Pro 2011, High Sierra 10.13.4) The Wi-Fi icon in the menu bar is displaying as empty. When I open Network Preferences and press “Turn Wi-Fi On”, nothing happens.

I have tried making the Wi-Fi service inactive, deleting it, then restarting the MacBook and adding the service back. 

This fix actually worked, but the problem returned after about thirty minutes. 

Since then, I have simply been repeating the process every time the Wi-Fi turns itself off, but it is very inconvenient and I hope it is not the only fix.

I’m afraid that the fact that the Wi-Fi turning itself back off again indicates that it’s a hardware issue.

After seeing a response to another user who had a similar problem, I have also tried using Terminal to “cycle the power to my wireless card”. It had no effect.

After restarting the MacBook again, it now says “Wi-Fi: No hardware installed” and will not let me create a new Wi-Fi service.

After another reboot I was able to turn WiFi on again, but it turned off after about ten minutes. I imagine that I will sometimes get “No Hardware Installed” again in the future.
Google's answer to "wifi no hardware installed mac"

This OSX Daily article from 2016 suggests that you need to reset your NVRAM and the SMC to solve the problem.