Try this and see if it helps you.
Go to Settings>General>Use Side Switch to>Lock Rotation. After you set the side switch to lock rotation, test it. Flip the side switch so that you can see the orange dot above the switch. OK - do you see a padlock icon in the upper right corner? If you see the lock icon, them the screen should be locked and the screen should not rotate.
If that all checked out OK, flip the switch the other way to unlock your screen and rest it by rotating the iPad. Does the screen rotate like it should? If it does, then you now have correctly set the side switch to lock the rotation of the screen.
Now .... Double tap that hated home button. Swipe to the right in the task bar at the bottom of the screen. Do you see a speaker icon all the way to the left? If you do - does it have a line going through it? If it does, tap in the icon and the line going through the speaker should go away. Tap the home button.
Now see if you have system sounds like keyboard clicks, try typing a note in the notes app. If you hear the sound of the keyboard you have successfully unmuted system sounds.
Now you should be able to lock the screen with the side switch and mute system sounds in the task bar.