Windows is Stuck at the Welcome Screen or Lock Screen

Under specific circumstances, your Windows system may become stuck at the Welcome or the Lock screen preventing you from reaching your desktop. The computer could enter into a restart loop or manage to load normally from time to time. The causes for this serious issue are varied, as it can be brought on by a failing hard drive that prevents the system from reading crucial startup files, incompatible or corrupted software that requires an abnormal amount of time to load, malfunctioning or corrupted system files and more. 

Being unable to reach their desktops means that users will have to rely on either starting the system in Safe Mode successfully or running the Advanced Startup Options. As a last resort, they may need to use a bootable media drive to start Windows. 

Run an SFC Scan

The Windows System File Checker (SFC) is a powerful tool designed to detect errors or corrupted system files and fix them. It also can replace any core system files that are missing. To start an SFC scan:

1. Open Command Prompt or Windows Terminal (Administrator).
2. Type sfc /scannow and press Enter on your keyboard to execute the command.
3. Wait while Windows is scanning the system for errors and trying to fix them. The process may take a while depending on your system's hardware specifications. 

Run a DISM Scan

If SFC didn't find any errors or fail to repair them, try using the Deployment Image Servicing and Management (DISM) tool. DISM can fix issues, such as Component Store Corruption that could be preventing the SFC scan from doing its job properly.

1. Open an elevated Command Prompt window.
2. Type DISM /Online /Cleanup-Image /restorehealth and press Enter to execute the command.
3. Wait for the DISM tool to complete its check and fix any detected errors.
4. Restart the system and run DISM once more so that the tool can replace any remaining corrupted files.

Try the System Restore

1. Reboot the system until you see the Automatic Repair message.
2. Open 'Troubleshoot,' and select 'Advanced options.'
3. Now, choose 'System Restore.'
4. Enter the username and password for your Admin account.
5. Click 'Next.'
6. Select a suitable restore point and follow the on-screen instructions.
7. Check if the problem has been resolved.

Run the Startup Repair

For this solution, you will need a bootable USB drive with the chosen Windows version. 

1. Set the first boot drive as USB via the UEFI or BIOS of your system.
2. Connect the USB drive and restart the computer.
3. On the Windows install screen, click on 'Repair this PC' located in the lower-left corner.
4. Select 'Troubleshoot,' 'Advanced options,' and then 'Startup Repair.'
5. Wait for Startup Repair as it scans and tries to fix any software driver issues, missing or corrupted system files, configuration settings, registry settings, and disk metadata. 
6. Afterward, remove the USB and restart Windows normally. Hopefully, the system will load normally without any more problems.