Mac accidentally erase. No back up.

Was this method from Apple used >> Use Disk Utility to erase an Intel-based Mac

Then use this method from Apple >> How to reinstall macOS

Follow these guidelines during installation:

• If the installer asks to unlock your disk, enter the password you use to log in to your Mac.
• If the installer doesn't see your disk, or it says that it can't install on your computer or volume, you might need to erase your disk first.
• If the installer offers you the choice between installing on Macintosh HD or Macintosh HD - Data, choose Macintosh HD.

Suki12ctg Said:

"Mac accidentally erase. No back up.: What can I do.? No experienced obviously. No data on computer. I thought it would it reset to original settings

-------

Two Things:

A. Install High Sierra:

You need to install High Sierra. To do so, create and use a High Sierra USB Bootable Installer for High Sierra. Use a USB Flash Drive of 16GB to create it.

B. Learn from this:

Know to always have a backup of your Mac, that way you can have something to restore your Mac from, should anything go wrong in the future.