I don't really get it, but:
If your game is in german and you want it to be in english, there is NO WAY you can do this, other than buy the game in english.
But: European games are often multilanguage, so that you can choose while installing if you want to have the game in (usually) german, french, italian, spanish or english (for the uk'ers). If your game isn't multilanguage (it's possible that complex games are not multi, but one language, in this case german), you basically have no other choice than buying the english version. (You won't ever find german to english patches for games but there are a few english to german ones

)
Hope this helps.