I recently made the switch to Android Studio as my default IDE for Android development. When designing my UI I normally use the palette in the design view to assist in arran
Android Studio 2.3.3, and the answer I was looking for:
Window -> Restore Default Layout (Shift+F12)
You have to be in the 'Design' tab (as opposed to the 'Text' tab) at the bottom of the middle window (the one that shows the phone).
The palette can be shrunk to 0 width. This can be expanded by hovering next to the left edge of the design window, and finding the right-most expand position.
If you have only the designer and the properties showing and the Properties is on the right, you can get the palette back by switching to a left or right view.
Try to switch between Design/Text tabs at the bottom left of the editor.
My solution was traversing
src->main->res-layout->content_main.xml
then open content_main.xml