Android Phone Screen on PC debug

It's likely that the device is no longer authorized on ADB for whatever reason.

ADB path C:\Users\LoggedinUser\AppData\Local\Android\sdk\platform-tools

1. Check if authorized:

<ANDROID_SDK_HOME>\platform-tools>adb devices
List of devices attached
4df798d76f98cf6d        unauthorized

2. Revoke USB Debugging on phone

If the device is shown as unauthorized, go to the developer options on the phone and click "Revoke USB debugging authorization" (tested with JellyBean & Samsung GalaxyIII).

3. Restart ADB Server:

Then restarted adb server

adb kill-server
adb start-server

4. Reconnect the device

The device will ask if you are agree to connect the computer id. You need to confirm it.

5. Now Check the device

It is now authorized!

adb devices
<ANDROID_SDK_HOME>\platform-tools>adb devices
List of devices attached
4df798d76f98cf6d        device