nvidia - Ubuntu 18.04: graphics card driver fails

I recently installed Ubuntu 18.04 and the installation process went very well but when trying to change the brightness of the screen and I was unable to do that so I opened Software and update center to install graphics card driver and I found two proprietary drivers and one is nouveau X.ORG (this was enabled by default) so I chose to install the latest and the recommended one (Nvidia driver 390 as you can see in the picture)

screenshot 1
so after successfully installing the driver I rebooted the system but nothing was changed, I still unable to change the brightness and also can't change between the Intel graphics and Nvidia using the Nvidia X server configuring program so I deleted the driver and tried manually installing it from Nvidia website but I got the same result with no luck but when I tried to change the installed driver from software and update center I got a new option saying continue using manually installed driver and the other options were disabled (see the picture) screenshot2so I had to remove the installed driver using the terminal (I did this using purge Nvidia*) then tried to install an old driver (Nvidia driver 340) but after rebooting the system was unable to boot up so removed driver and now I feel frustrated because I don't know what to do.
I have MSI GE60 laptop with the following specifications:
CPU:i7 3630QM
GPU:Nvidia GTX660M
RAM:8 GB