Boot Camp

I have MacOS and Windows 10 in my MacBook Pro-retina
display. I switch from one OS to another through Boot Camp. After installing
the new High Sierra update I switched to Windows. Now I wish to go back to my
MacOS and the bootcamp.exe application does not work. The Boot Camp control panel
just show the Windows options. I am stuck in Windows. How do I fix boot camp?
How can I go back to my Mac OS from Windows?