i recently installed windows to my mac and i have just formatted my mac os hard drive on windows by a mistake. now i cannot start my mac on mac os.how to reinstall mac os to my mac...please help..

You can try reinstalling by rebooting and holding command+r to recover the OSX install. Warning: This will NOT install Sierra. It will install whatever OS the Mac came with. For more info click here -----> How to reinstall macOS - Apple Support

Hey abstainer,

do you have a bootable macOS USB? If so, use another OS X computer. Insert your USB. Download macOS from the featured tab on the app store. Quit the OSX installer. Open Spotlight (the magnifying glass in the right top corner. Type in terminal. Type in this for Sierra:

sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ macOS\ Sierra.app

Example for El Capitan: sudo /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath

Yosemite:

sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ OS\ X\ Yosemite.app

Example for Mavericks: sudo /Applications/Install\ OS\ X\ Mavericks.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ OS\ X\ Mavericks.app. Replace /Volumes/MyVolume with your USB name. For example, if your USB is named USB, Change it to /Volumes/USB. Next time, use Boot Camp to install Windows. Don't make a new partition. Please tell me if this helped you!

i recently installed windows to my mac and i have just formatted my mac os hard drive on windows by a mistake. now i cannot start my mac on mac os.how to reinstall mac os to my mac...please help.

i want to ask if i can create a virtual machine and get this done it will help because there is no one with a mac beside me for now.

You can use a blank USB and use the commands I said earlier on another mac, if you have one.