WE HAVE A HUGE PROBLEM FOR OVER A YEAR

Hello,
everypone ive got a big big problem ,i bought a laptop in switzerland a year ago for me and my wife,but when i was installing it for the first time i chose german for the preset language.....then my wife informed me she knows as much about computers if not less please help us,i cant even try to solve problems without days of trial and error. p.s ive got programmes i dont even know what they do.....please help