Change Metro UI Language in Windows 8
Windows 8 CP | 12-03-2012
Some of your Metro Applications are in German? It's because your default language isn't supported and you have deleted all other languages from your system. In that case Windows 8 Consumer Preview will choose German language as default for Metro apps. To choose other, for example english, you have to add that language. Run Metro and type "add language". Choose language you want and add it.