What can I do if Wi-Fi icon is disabled?

First try a Forced restart Force restart iPhone – Apple Support (UK)

Then Settings, General, transfer or reset iphone, Reset, Reset network settings.

Good luck

слава україні

Because you tapped the Wi-Fi icon in Control Center. 

So the Wi-Fi icon turn to 'white' -> Wi-Fi Is deactivated.

To activate the Wi-Fi again, it will be turn on to 'blue' again.

And you will have Wi-Fi connection again.

To turn Wi-Fi Off or On, go to -> Settings -> Wi-Fi.

But why you turn Off the Wi-Fi network?

Did you check, go to iPhone's

Settings > Wi-Fi > switch Wi-Fi ON here

Also try Settings, Wifi, make sure it is turned on.

What about the reset of network settings?

If you are in Ukraine I don't know how you get round this but it looks like it may need repair service.

If you have computer and internet you could try backup, restore to factory, and restore from backup, but it is clutching at straws and a risk in your circumstances.

Good luck.

🇺🇦 слава україні 🇺🇦

Addition, based on your screenshot that message has to do with ->  Set up and use Notify When Left Behind in the Find My app

Set up and use Notify When Left Behind in the Find My app - Apple Support (IN)

I’ve had this same problem for a week. Network reset, back ups, start fresh nothing has worked. It’s an iPhone 12 Pro and is basically garbage to me. Can’t link to my watch or anything. All forms other than cell usage are disabled. The network reset worked one time then if you connect and use it the phone will work than basically freeze reboot and back to nothing.

Same problem with Control Center; WiFi is ON in Settings.