There is no setting on the device to enable/disable the accelerometer (the mechanism that rotates the screen). I would attempt to do the standard troubleshooting by power cycling the device. If that doesn't work, I would attempt a master reset. If the master reset still doesn't work, we may need to do a warranty claim for you (given there's no physical or liquid damage). You can call the warranty center at 866-406-5154 directly or you can PM me, and I'll check your warranty eligibility.
Let us know the resolution on your issue!