So you have fucked up the English (Default, ID=1) Language pack?
You want to restore the default words?
1. Go to your Admin Panel > SQL Management > SQL Toolbox
2. Run the Following Query:
Sorry, but you need at least 25 posts and 5 hours online time to unlock hidden content.
So that's done!
3. Now go to your Admin Panel > Languages > Manage Languages
Recache the language Pack.
Your Language Pack is restored!