Please provide more information on this problem,
Was your device upgraded from Windows 10 to 11?
1
If so, you have a 10 day time period in which you can roll the system back to Windows 10, open the Settings App, then go to System - Recovery, there, you should find the 'Go Back' option, if that is available, it is best to backup your files first in case the process goes wrong.
2
If your system was upgraded from Windows 10 to Windows 11 and it has been more than 10 days since the upgrade, then the option to roll back will not be available, you would need to backup your files, create a bootable Windows USB and then boot the PC from that to clean install Windows 10.