My MacBook Pro 2014 got stuck while I was working. I had to force restart it. However, after it was turned on, it showd a question mark with a folder. I booted into Recovery Mode and went to Disk Utility but couldn’t find the internal SSD anymore. There’s a disk 0 and OS X Base System.
Try the following steps to reinstall macOS:
- .First, press the power button to turn off your Mac.
- Turn on your Mac, then immediately press and hold Command-R.
- Release the keys when you see the Apple logo.
- Click Disk Utility > Continue.
- Click View > Show All Devices.
- Select the top-layer physical disk and click Erase.
- Name it as Macintosh HD.
- Choose APFS as format if running macOS High Sierra or later; otherwise, choose Mac OS Extended (Journaled).
- Keep GUID Partition Map as the scheme.
- Click Erase.
- Exit Disk Utility.
- Choose Reinstall macOS and click Continue.
- Then follow the instructions to reinstall the system.
You could also use Option-Command-R at startup to boot into Internet Recovery Mode to reinstall the latest macOS available to your Mac.
Try booting your Mac from a exernal drive to reinstall macOS.