Use Bootrec.exe in the Windows RE to troubleshoot startup issues
When you use the Recovery Environment (Windows RE) to troubleshoot startup issues, first try the Startup Repair option in the System Recovery Options dialog box. If this does not resolve the issue, or if you have to manually troubleshoot additional issues, use the Bootrec.exe tool.
"Bootmgr is missing Press Ctrl+Alt+Del to restart" error when you start ...
Look for a tab in the BIOS Setup Utility that is labeled Boot Order, Boot Options, or Boot. Following the directions on the screen, use the arrow keys to go to the Boot Order, then press Enter.
How to perform a clean boot in Windows - Microsoft Support
A clean boot starts Windows with only essential drivers and startup programs, making it easier to identify and troubleshoot background software conflicts affecting apps or games. Unlike starting Windows in Safe Mode, it provides greater control to isolate the source of a problem
Configure Startup Applications in Windows - Microsoft Support
Learn how to optimize system performance by managing startup applications in Windows.
Windows Recovery Environment - Microsoft Support
Startup Settings: Allows you to change various startup options to help troubleshoot and resolve issues with Windows. To learn more, see Windows startup settings.
Recovery Drive - Microsoft Support
Start your device from the USB drive that was created with Recovery Drive. The process to boot from a USB drive may vary by manufacturer, so refer to your device's manual if needed. Create a recovery drive to reinstall Windows in case you experience a major issue such as hardware failure.
Startup Repair - Microsoft Support
This tool is particularly useful when your computer is experiencing issues such as missing or damaged system files, corrupted boot configuration data, or other startup-related problems.
System Configuration Tools in Windows - Microsoft Support
It provides options to customize the startup process, including the ability to enable or disable software, control startup services, and access other advanced system settings.
Recovery options in Windows - Microsoft Support
Windows provides several recovery tools to help you troubleshoot and restore your PC when issues occur, such as startup failures, update problems, or malware infections.
Use the System File Checker tool to repair missing or corrupted system ...
When critical Windows system files are missing or corrupted, your operating system may begin to malfunction. Common symptoms include Windows features not working properly, system errors, or Windows becoming unresponsive or freezing.