This happens if the game tries to load a font style that does not support English characters. Ensure you did not delete the default .fnt files inside the game folders.
This guide covers everything required to safely download, install, and optimize the Need for Speed: Underground 2 English language pack for the best possible gameplay experience. Why Quality Matters for Language Packs nfs underground 2 english language pack better extra quality
To help tailor these steps, let me know you are currently running and where you downloaded your copy of the game. I can then provide specific file links or exact registry paths if needed. Share public link This happens if the game tries to load