Hi @Thomaskarl16,
the 304 Nvidia package is for older GPU's (legacy) so try the following:
Boot into recovery mode and activate "Network" (a cable network connection is required) then drop to "root" and type the following command:
sudo apt-get remove nvidia-304 && sudo apt-get install nvidia-367
Retsart with Ctrl + Alt + Del, DO NOT CLICK ON RESUME!. 
See also: