models are invisible

Hello. I recently installed SOLIDWORKS on a second computer using my student license. Unfortunately a problem occured. I can´t see the volume models, which I´m drawing. The scetching tool can be used properly, but when I want to extrude the model, the whole body disappears. Then, I can only see the edges when marking the model.

So how can I make the forms that I draw visible?

Thank you in advance!