1. Use Task Manager to close WhatsApp
Press Ctrl + Shift + Esc will bring up Task Manager.
Select WhatsApp from the Processes menu.
Click the End task button to end the process.
2. Fix the WhatsApp Desktop App using Settings
Launch the Windows Settings app.
Navigate to Apps > App & Features.
Select WhatsApp from the list of apps and then click Advanced options.
Choose the Reset option.
3. Run the Internet Troubleshooter
Navigate to Settings, then Update & Security.
Select Troubleshoot from the left-hand menu.
Select Additional troubleshooters.
To begin, go to Internet Connections > Run the troubleshooter.
4. Use the Same Wi-Fi Network
If you intend to use the WhatsApp Desktop app, connect your computer and phone to the same Wi-Fi network.
5. Reinstall the application
Remove the app from the Settings menu and then download and reinstall WhatsApp Desktop again.