Answer by DeepSpace101 for Windows 8.1 missing font files after restart

Had the same issue and the selected answer didn't work, I just kept getting an endless crash of the UI (Explorer.exe) after logging in from a garbled login screen. So here is what worked off the command line.

On a working Mac/PC/Linux machine ...

1. Download the default Windows 8.1 font pack from this post (direct link). The SHA256 hash of the .zip is

openssl dgst -sha256 Windows8.1-Default-Fonts.zip

SHA256(Windows8.1-Default-Fonts.zip)= d2c0cccc8f77f4d8198161cb452c9758608fdb70d64a9347c0b1d911b5d1af49

2. Extract the .zip file above to a USB flash drive. Example: to D:\Fonts so you'd have something like D:\Fonts\Arial.ttf and so on.
3. Download the powershell scripts from this post (direct link)
4. Extract the .zip file to the same USB flash drive, to say D:\FontScripts\ so you have something like D:\FontScripts\Add-Font.ps1

On the affected computer ...

1. Boot into Safe Mode with Command Prompt (see details below)
2. cd c:\Windows\Fonts (enter) and del /f /s /q *.* (enter)
3. type PowerShell (enter) into the command prompt
4. type Remove-Item "hklm:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts" (enter). We remove this because it's corrupt.
5. Insert the USB flash drive
6. Type D: (enter) then cd D:\FontScripts (enter)
7. Type .\Add-Font.ps1 D:\Fonts (enter). You'll get errors about a missing registry settings. Ignore for now.
8. Reboot. This will rebuild hklm:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts that we just removed in #4 above
9. Boot into Safe Mode with Command Prompt (same as step #1)
10. type PowerShell (enter)
11. Type D: (enter) then cd D:\FontScripts (enter)
12. Type .\Add-Font.ps1 D:\Fonts (enter)
13. Reboot.
14. Get a beer and don't install corrupt fonts.

Booting Windows 8.1 into safe mode

Detailed as option #2 in this blog post, listed here for completeness.

1. Reboot the affected computer till you hit the login screen
2. Click the power icon in the bottom right corner. If your fonts are REALLY messed up, this will just be a square box :(
3. Press the SHIFT key and click the last menu option (it reads Restart on good systems)
4. Select Troubleshoot => Advanced options => Startup Settings => Restart
5. When it restarts, select #6 i.e. Safe Mode with Command Prompt