As with all of my tips, I do not suggest using this if any of what I am about to explain sounds foreign to you!
That being said, I give you the ability to choose your boot in to Safe Mode when you need it since you no longer have the F8 option and the alternative currently is to HOPE that windows 10 boots to the advanced boot menu eventually when numerous attempts of booting normally fail. Quite often you will get the 'windows could not start-we are attempting to fix this and restart your computer" or something like that.. this method can probably help you as in most cases if your system does boot to safe mode then at least you know windows is still intact and is not corrupted to the point where the installation needs to be installed again. Or in the case where windows is simply not even detected which can happen if the drive appears to have disappeared.
The tip: (from ITPro)
Nothing gets you out of Windows trouble like Safe Mode, which is why it's inexplicable that you can no longer enter it by pressing F8 or Shift+F8 at boot. Although it's still available in Windows 10, you have to boot into Windows first, then either restart holding the left Shift key or via an option within Update & Security in the Settings app. Neither method is helpful if your PC can't boot into Windows in the first place.
You can't get around this, which is why it's helpful to create a boot time Safe Mode option before trouble arrives. Hit Win+x and select Command Prompt (Admin), then type bcdedit /copy {current} /d "Windows 10 Safe Mode" and hit Enter. From the Start Menu type msconfig, run System Configuration in the results, and navigate to the Boot tab. Highlight the Windows 10 Safe Mode option you just created, tick Safe boot and select Minimal under Boot options and - if necessary - reduce the Timeout value so you won't be inconvenienced - the minimum is three seconds. Tick Make all boot settings permanent (in fact you can simply return here to delete the Safe Mode entry) and click OK.
You can repeat these steps, substituting suitable names in quotes at the Command Prompt, to create shortcuts for Safe Mode with Networking (tick Network rather than Minimal in System Configuration) and Safe Mode with Command Prompt (Alternate shell).
