Hi Hanny,
If your Surface Pen no longer interacts with the screen, replacing the battery usually resolves the issue.
If replacing he battery doesn't resolve the issue, you may try these solutions:
Restart your Surface device.
If after restarting the device doesn't work, force shutdown the device.
- Press and hold the power button on your Surface for 30 seconds and then release it.
- Press and hold the volume-up button and the power button at the same time for at least 15 seconds and then release both. The screen may flash the Surface logo, but continue holding the buttons down for at least 15 seconds.
- After you release the buttons, wait 10 seconds.
- Press and release the power button to turn your Surface back on. You should see the Surface logo.
Pair your Surface Pen.
- On Surface Pen, press and hold the top button until the LED light blinks to make it discoverable.
- On your PC, select the Start button, then select Settings > Devices > Bluetooth & other devices.
- Make sure Bluetooth is on, then select Add Bluetooth or other device > Bluetooth. Choose Surface Pen in the list of devices. Follow any other
instructions if they appear, then select Done.
Run Hardware and Devices Troubleshooter.
- Type Troubleshooting in the search box, click Troubleshooting.
- Under Hardware and Sound, choose Configure a device. The Hardware Troubleshooter will open.
- Click on Next to run the Hardware and Devices Troubleshooter.
- Choose the one you want to fix and click on Next. The Hardware and Devices Troubleshooter will try to fix the problem with the pen.
You may also check this article about troubleshooting Microsoft Surface Pen issues.
Let us know if you need further assistance.