Nobody said this was going to be easy
Ok on the XP install disk the default fonts will be in the folder i386. They are compressed so you have to use the EXPAND command to uncompress them.
First try to determine which fonts may be corrupted.
Then
1) create a folder "Fonts" on the root of the C: drive
2) Place your XP disc in the CD/DVD drive. Hold down the shift key while you do this until the disc loads. This prevents autoplay. If you get some warning about holding down the shift key just click on cancel. If autoplay kicks in anyway just cancel out of the screens.
3) Click the start button and pick "Run" - in the box type "cmd" (without the quotes)
4) This should open a command line box that should say "CMD.EXE" somewhere in the title.
5) at the ">" prompt in command box type "expand d:\i386\*.TT_ C:\Fonts\" without the quotes and press enter (substitute D: with whatever your CD/DVD drive is if not D: e.g. E: )
6) then type "expand D:\i386\*.fo_ C:\Fonts" without the quotes and press enter
7) Type "cd \fonts" etc.
8) type "ren *.tt_ *.ttf" etc.
9) type "ren *.fo_ *.fon" etc.
Ok, this will expand all the stock fonts from the install disk most of which you probably don't have installed.
Go back to the Fonts folder from the Control Panel and delete the corrupted fonts then from the "File" menu of the Fonts folder pick "Install New Fonts" and find the C:\Fonts folder you created earlier. Hold down the control key and pick the fonts you want to install (make sure the "Copy to Fonts Folder" box is checked). Click "Ok" and the fonts should be installed.
Possible snag: Font(s) may be in use when trying to delete them. In that case you'll get an error message. We'll cross that bridge if that happens.
Note: you need admin rights to delete and add fonts.