ok. i think i did what you've told.
i've typed these things into the command line:
takeown /r /f C:\ProgramData\Application Data <return> icscls C:\ProgramData\Application Data /grant <***> <return>
and then i could open that 'application folder'.
a weird thing happened then. the 'application data' folder seems exactly like the 'program data' folder, containing another 'application data' folder. If i keep opening 'app data' folder, the file path will be:
C:\ProgramData\Application Data\Application Data\Application Data\Application Data\Application Data
Am i looking in the right place here? I just want the wmp database file. I can find 'wmp' folder in under 'program files' but not sure which file to backup.