reinstall my only option?

Makosuke

macrumors 603
Aug 15, 2001
6,166
350
The Cool Part of CA, USA
I thought the install DVD would give you the option to add languages after the fact, so you might boot into it and see if that's an option. If not, then yep, nothing to do but reinstall. (I haven't used monolingual, but it's also worth noting that if it wipes languages from all applications, it may have also done so for apps that the OS has no control over, so you'll have to reinstall them from downloads or the original discs, regardless of whether the above works or not.)