Somehow my TED switched to another language. When I go into Preferences | Appearance there is no dropdown in the Language box for English.

Any suggestions how I get English back?

Same issue here this past week. Luckily I speak french but would prefer english. Full uninstall re-install??

Yea, Mine has dropped to "idioma- catala" a few times also.
It is recoverable by realizing that "English" has different spellings/ appearances in different languages: in catala it appears as "angles" ----

It seems to require a quit and start of the program to complete and lock-in the change.

This happened to me too, what I did to fix this:
1)open ted.jar with 7zip/winzip/other. Its in the installation folder.
2)go to \ted\translatons
3)delete all non english translation files. The english file is the ddefault: tedLang.properties
4)edit translations.txt, delete all lines.

heres my edited 0.972 jar, zipped jar (with the scraping fix too)
http://www.mediafire.com/?hfqr4xqjjojbah3