Hi Alvin777,
it may be due to a permissions issue. You can try running the command prompt as an administrator to see if that resolves the issue.
To do this, right-click on the Command Prompt icon and select "Run as administrator". Then, try running the DISM command again.
If you are still experiencing issues, you can try running the command with the /Source parameter to specify the location of the Windows installation files. For example, you can try running the following command:
dism /Image:G:\/Cleanup-Image /RestoreHealth /Source:WIM:X:\Sources\Install.wim:1
Replace "X:" with the drive letter of the Windows installation media, and "1" with the index number of the Windows image you want to use.
Hope it helps.
Best regards,
Lei