MacBook Pro WiFi suddenly stopped working with exclamation mark on it

The usual wifi signal with an exclamation mark through it means your computer is connected to a network but cannot reach the Internet. That usually means something like:

1. There is an issue with your wifi router, your modem (of course the router and modem might be the same device) or your ISPs Internet service;
2. An issue with the Wifi card (although that is extremely unlikely - a hardware issue that allows you to connect to a network but not otherwise be useable is hard to imagine);
3. There is other software on the computer interfering with connectivity. VPN is a half-connected state are a common cause of that).

Have you tried rebooting the computer to see if this fixes it (and/or rebooting in Safe Mode to prevent third party programs from automatically loading)?

Are other computers on the same Wifi able to connect (often people don't realize this is an issue if other devices are connected because they fail to remember those are on Ethernet or can fall back to cellular)?

I think I can only give you possible solutions based on the information you provide - and if we provide possible options and then you respond with completely new information then this is going to take longer.

So, let's go back to basics. You say that you see no wireless card info in the HW when go into the "About this Mac" info. You similarly say that you cannot run wireless diagnostics. So...

1. When you try to run wireless diagnostics, what exactly happens? What error messages or dialog boxes are generated and what do they say?
2. Under System Settings>Network, what info is displayed by the Wifi adapter in the sidebar? What is the network status? Are you connected to a network? Does it give you a list of networks to connect to at all when you click on the Network Name drop down box?
3. What happens when you reboot?
4. What happens when you reboot in Safe Mode?