You cannot change the settings in the font substitution table from some device fonts back to TrueType fonts on a Windows Vista-based or Windows Server 2008-based computer
On a Windows Vista-based or Windows Server 2008-based computer, you have a printer on which some device fonts are installed. On the computer, you change some fonts in the font substitution table of the printer from TrueType fonts to the printer’s device fonts. However, you cannot change the settings back to the original TrueType fonts. Therefore, if you have a character that does not print correctly by using the device fonts, the correct output for that character cannot be obtained.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB959221.