I found a nice article about re-ghost items (specially for master pages and page layouts)
http://mosshowto.blogspot.nl/2008/10/re-ghost-master-pages-sharepoint.html
http://mosshowto.blogspot.nl/2008/10/re-ghost-master-pages-sharepoint.html
Dismount-SPContentDatabase 12345678-90ab-cdef-1234-567890abcdef http://technet.microsoft.com/en-us/library/ff607764.aspx
This way it will dismout the content DB and now you can add the
content DB to the web application from central admin or use the below
command to mount it
Mount-SPContentDatabase “MyDatabase” -DatabaseServer "MyServer" -WebApplication http://sitename
http://technet.microsoft.com/en-us/library/ff607581.aspx