Side Switch Missing

I'm guessing you mean the power button. The side switch controls mute and lock rotation and was removed on iPad Air 2's. If the power switch is missing it all depends if you have Apple Care what happens next. Apple replaces iPads with refurbished models and the cost depends on your coverage.

If you decide not to have your iPad replaced you can use Assistive touch in accessibility. Go to settings> general> accessibilty> Assistive Touch> on. It gives you a onscreen button and menu to use instead on the power button.

You take a screen shot by pressing the home and sleep/wake buttons together for a brief moment. The sleep/wake button is on top of the iPad, not on the side. It is on the top right.