Thanks for your help, but I want to know how to fix such problems.
You learn how to do stuff by trying to fix problems yourself and from experience, not by having other people trying to solve your problems. Read documentation/wiki, try to install the drivers from repositories, if that doesn't work try to install the drivers manually. Live boot from another distribution to see if it works there, if it does then see what drivers are being used so that you have a comparison and can try installing the same drivers. Search log files or system journal for error messages, google the errors you don't understand, try running a command on the command-line and see what happens. Try to manually start your graphical environment and see what errors you come across, if you don't understand the error google the error.
Instead of using the nvidia driver trying using the nouveau driver and see if that works. Find out if your graphics cards has any support for anything special, ie bumbelbee, look what you can find about that. There are lots things you can do you just have to be creative. Have you even tried installing the nouveau driver? --> xserver-xorg-video-nouveau , did you try installing firmware-misc-nonfree?