Trying to reinstall OS Sierra I've a Mac Mini and I tried to reinstall Sierra yesterday.


I used Command + R at the log screen
Erased my Hard Drive
Click on Reinstall macOS Sierra


But when it was close to finish my internet dropped because of the rain and the reinstall failed. I tried again but nothing happened, so I restarted and now I can't access the recovery screen. My Mac boots directly to a grey folder with a question mark and the Command + R doesn't work.

What can I do now?
Internet recovery does depend on the network - so if your network was what made the first Command+R boot work, you will need to get back to a working network.

Most Macs don't erase the local recovery HD so you wouldn't likely have "shot a gun towards your own foot" if you simply erased the Macintosh HD and you would still be able to boot to recovery locally. 

Only if you repartitioned the entire physical volume would you have erased your own recovery.

As to the fix - you could make a recovery drive on another Mac that is working and has an internet connection or take your Mac to a working network and try internet recovery.


How do I boot into Internet Recovery on a iMac?
https://support.apple.com/en-us/HT202481 - lists the network requirements for internet recovery
https://support.apple.com/en-us/HT204904 - how to reinstall macOS