<random guess>
Did you set SL to run in Korean or Japanese?
</random guess>
Make sure the viewer isn't running and open Explorer (the normal kind) and in the address bar type (and enter after): %APPDATA%
(That should put you in the appropriate X:\Documents and Settings\username\Application Data\ folder)
Open the "Second Life" folder there, then "user_settings" and you see various settings*.xml files (or one depending on all kinds of viewers you've previously installed).
The current WindLight uses the settings.xml for me (instead of the logical settings_windlight.xml), but it won't hurt to check for each one there.
Open the file(s) in Notepad and look for (they're sorted alphabetically):
From: someone
<!--Language specifier (for XUI)-->
<Language value="en-us"/>
If it's not present, SL is using the system default so just copy/paste-add the bit above in case it's confused, if it's present and has something other than "en-us" ("jp" for Japenese for instance), simply replace it with "en-us" and open the viewer again to see if it helped.
---
In case it sounds too intimidating the visual run-through is:
"Preferences" - the top right button of the 4 blue buttons at the bottom (although it seems the blue buttons are actually white highlighted for you
)
The "General" tab (the very top button on the left) and the drop-down at the very button (English should be listed in English, but just in case it's the second option there).
"OK" is the left-most blue button of the three at the bottom.
And then just close the viewer and reopen to see if it helped
.
