Right-click the file you want to take ownership of & go to properties.
Go to the 'Security' tab.
Click on 'Advanced'.
Go to the 'Owner' tab & click edit.
Click on your name & apply.
Exit the properties to apply changes
Go once again into the properties of the file.
Go once again to the 'Security' tab.
Click on your name and then edit, give yourself full permission on the file.
Apply, close and you're done.