Grey wifi icon & not responding

Ok, thanks.

I suggest by starting with running Apple Diagnostics to see if it uncovers any hardware issues with your notebook. Please post back your results.

Ref:

• Use Apple Diagnostics to test your Mac - Apple Support
• Apple Diagnostics: Reference Codes - Apple Support

Ok, thanks for giving those both a try.

My "last resort" steps are as follows:

Step 1

• Open a Terminal session. The Terminal application is located in /Applications/Utilities.
• At the command prompt, enter: ifconfig -a <enter>
• Locate the network interface that is giving you trouble. (Note: Typically, the AirPort = en1)
• Look to see if Terminal indicates the problematic interface is not enabled.
  • Enabled =
    • flags: <UP ...
    • status: active
  • Disabled =
    • flags: <DOWN ...
    • status: inactive
• If not enabled, enter the following command: sudo ifconfig en1 inet up <enter>
• Verify success. Enter: ifconfig en1 <enter>
• If unsuccessful, go on to the next step.

Step 2

• In Finder, go to /Macintosh HD/Library/Preferences/SystemConfiguration
• Move (not copy) the NetworkInterfaces.plist & com.apple.airport.preferences.plist files to the macOS Desktop.
  • Note: These two files will be rebuilt by macOS to their default settings. You may need to re-enter your network info to connect to your Wi-Fi network.
• Restart the computer.
• Verify, whether or not, that your Mac have connectivity.

If neither of these steps help, it's time to contact Apple Support directly for further assistance with this matter. To do so, simply select the "Get Support" link in the upper right-hand side of this forum's web page.

Ok, let's start with a few simple troubleshooting steps.

Step 1: Boot up in Safe Mode - Try booting up your Mac in Safe Mode to see if it now recognizes the built-in AirPort wireless adapter.

Step 2: Boot up in normal mode - Create a new user account. Log out of your existing account, and then, log back in with the new account.

For each of these steps, verify whether your Mac recognizes the adapter ... or not.

What exact model is your MacBook Pro and what version of macOS is it currently running?