Here is a list of things to do if your phone screen is not rotating:

1. Make sure your device is not in the locked orientation mode. If it is, unlock it and try rotating your screen again.
2. Check if you have an application running that prevents the orientation from changing. If so, close the app and try toggling your screen again.
3. Restart your device and see if the problem persists.
4. Check if the auto-rotate setting is enabled in your phone’s settings and try toggling it on and off.
5. Check if your device’s gyroscope is working properly. If it is not, you may need to replace it.
6. If the problem still exists, consult an expert.