yaswanthlavu Said:
"My screen is broken and my mac is stuck on question mark start up screen i can only connect my external display when the screen is closed. How do i factory reset my mac?"
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How would you define "broken"?
Is there physical damage, or is it just this boot issue you are having?
Install this Anew:
Your drive has been erased. So, you need to install this anew.
Start Here: If your Mac Starts Up to a Question Mark - Apple Support
You'd:
1. Mount the Drive:
Boot into Recovery Mode (Intel or Silicon) . Then, using Disk Utility, see if the Hard Drive is seem. If it is, then see if you need to click the “Mount’ button for it. Try rebooting once more. If of no success, then click unmount button, and then the mount button. Try rebooting once more.
then...
2. Install the macOS:
Use a USB Bootable Installer:
Try installing using a USB Bottle Installer. Using another Mac, go here to create one: How to create a bootable installer for macOS - Apple Support