That setting isn’t in the phone’s regular Settings app and it’s very easy to open without even meaning to.
Luckily, it’s very easy to turn the Home Screen Rotation setting back off. Here’s how:
Note: The actual settings on Android devices can vary a bit from device to device. Therefore you should use the procedures detailed below as general guides.
1 – Tap and hold your finger on a blank area of your phone’s Home screen until a menu pops up.
2 – Tap Home settings.
3 – Toggle the “Allow home screen rotation” setting to Off (the slider should turn from green to gray).