This is the Start menu screen. click on the windows icon on the left end of the taskbar and you should get back to where you were.
Also if you right click that icon you get the alternate menu.
Click on the last icon on the right end of the taskbar and you will get the Action Center and you may see one of the boxes with Tablet Mode and if you are in Tablet Mode it will be highlighted. If highlighted click on it to turn off.