This can naturally have many causes. You may just feel uncomfortable after moving to where you are studying, feel alone in an unfamiliar place and miss family and friends. Alternatively, the environment may be familiar, but the focus of studying at this university isn’t really in line with your own interests. You may have decided to commute to university every day and that doesn’t feel right any more.
If you are sure that the subject is the right one, but the university isn’t a good match, then you have already achieved a great deal. You can then re-navigate your course to find your own subject and degree programme at a new university. You can search for a degree programme in the city of your choice here:
University panorama (only in German available) is an information portal of the Agentur Für Arbeit (Federal Employment Agency) and is aimed primarily at prospective students. The map of Germany provides an overview of all universities with state degree programmes.