Where did the sidebar on s4 go.?
What are you talking about? The multi-screen option?
If you mean the little side tab that has app shortcuts, just hold down the back button and it will come back.
Isn't that just the launch area for multi-screen? Try launching one app from there, then launching a second dragging the second icon down to the bottom half of the screen.
hold your back button at the bottom of the phone, should bring it back
Separate names with a comma.