Search in your old firefox data folder this file "localstore.rdf". this file contains the informatio about the layout of firefox. maybe solve your problem

I found "localstore.rdf" — but what do I do with it?

try to copy this file in your new profile folder of firefox. See Profiles - Where Firefox stores your bookmarks, passwords and other user data

I did that, thank you sir. And restarted Firefox. But the mime persona of mine didn't appear. The rfd I moved into profiles/default is 17K as opposed to the one already there, which is 2K.

It didn't want to replace the existing rfd file and I then clicked "keep both." Then I changed the names so the old rfd would appear to be the standard one and the other now has "=" added to the file name so it won't be the default but can be changed back if needed.

You must delete the new file,the one of 2kb, and then copy the old version,the other who is 17kb. You don t keep both files.

Ok. Did that and restarted Firefox. No persona :-(

Firefox only stores your current persona. It's in your profile folder, as the files lightweighttheme-header and lightweighttheme-footer.You have to look for this file and copy them in the new profile folder of firefox. Also you can try to copy the personas folder in the folder of your new firefox profile.

  Additional personas may be saved in your disk cache. To retrieve them,

  1. Type about:cache?device=disk in the address bar and press Enter. Warning: if you have a large disk cache, Firefox may stop responding temporarily or freeze altogether.
   2.Look for images from http://www.getpersonas.com/static/...
   3.Click an entry for detailed information, then click the key: link at the top to view the image.
  4. If it's the persona you want, right-click the image and choose Save Image As. 

To find the links for images used by your installed personas,

   1.Type about:config in the address bar and press Enter.
   2.Press the big button to bypass the warning.
   3.In the search box, paste lightweightThemes.usedThemes
   4.In the search results, right-click lightweightThemes.usedThemes and choose Copy Value.
 5.  Paste the clipboard contents into a text editor and examine them. hederURL and footerURL are the images used by personas.

The persona I want is the one I created with the head of the woman playing the Mime character in the production of A THURBER CARNIVAL I directed a while ago.