First of all, are you from Germany?
Google's homepage geolocates what country you are in, and serves you with that country's homepage.
If you are using a proxy that is located in Germany, then you could also be presented with the German homepage.
I.e. Whatever country the IP you use to connect is associated with, you will get a matching Google homepage.
There is normally a link in the bottom right hand corner saying "
Go to Google.com".