Step 1: Boot up your computer and insert the Windows 11 installation CD or USB stick.

Step 2: Restart your computer and select the disc or USB drive to boot from.

Step 3: On the Windows Install Now screen, select 'Repair your computer.'

Step 4: On the 'Choose an option' menu, select 'Troubleshoot.' Then, in the Advanced options windows, make your selection.

Step 5: Select 'Startup Repair' from the drop-down menu. Following that, Windows Startup Repair will begin diagnosing your computer. When the process is finished, the Windows 11 startup problem should be resolved.