Mac only starts in windows

Hi, I can't access my Mac partition anymore. When I start up my MacBook it immediately goes to windows. When I try to start up my mac in safe mode it also goes straight to windows. Holding alt, or alt cmd R P doesn't work it just goes to windows. When you go to the Bootcamp assist on windows it won't show my MacBook partition and when you select startup with OS X is says it isn't able to find the startup volume. Soooo help I don't know what to do anymore.

I have a MacBook Air 13'' mid-2013 with 256 GB and update to High Sierra