I lost custom theme created in SP2007 site upon migration to SP2010 using content database upgrade. I read somewhere that I need to copy existing theme from the C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\TEMPLATE\THEMES directory into the new directory.
Edit the C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\TEMPLATE\LAYOUTS\1033\SPTHEMES.XML file and add a section for the new theme
This however causes an error when I try to access Site theme page. Any guidance would be helpful.