Hello, Lars-Erik Østerud.
Using the tool provided on the page https://www.microsoft.com/en-us/software-download/windows11 or https://www.microsoft.com/nb-no/software-download/windows11 (if it's more convenient for you) download and save the ISO image. Connect the image to a virtual drive and run the file from the virtual DVD setup.exe on behalf of the Administrator. Select the installation type "With programs and files saved...". This will not be a reinstall, but a fix with an update using an offline image. Please note that the process can be long and take up to several hours.