Please Help: Nvidia Drivers on Optimus Laptop Ubuntu 15.10

Question

so I tried to install the vulkan driver a couple of days ago, but it did not work so I tried restoring my system by first uninstalling the vulkan driver, then purging everything nvidia, then installing nvidia-352 and nvidia-prime. But now GL doesn't work so I can only use xfce (which I am writing this on). In my Xorg.0.log (http://paste.ubuntu.com/15101909/) I have this line: (EE) Failed to initialize GLX extension (Compatible NVIDIA X driver not found). So now all GL programs won't run. Currently I am using the 355 driver because some guy on the forum said it might work but it didn't fix the problem. Any help would be GREATLY appreciated. Notes: To be clear, I am no longer intending to install the beta vulkan driver. I have a muxless laptop so no, I can not disable the intel graphx card. And finally my graphics card is a GTX 960M.

EDIT: Here is the output of lspci -k | grep -EA2 'VGA|3D' http://pastebin.com/1aLhr4Th

EDIT 2: Here is the output of dkms status

    bbswitch, 0.7, 4.2.0-23-generic, x86_64: installed
    bbswitch, 0.7, 4.2.0-25-generic, x86_64: installed
    bbswitch, 0.7, 4.2.0-27-generic, x86_64: installed

EDIT 3: Here is what happens when I try to run a GL application:

    Xlib:  extension "GLX" missing on display ":0".
    Error: couldn't get an RGB, Double-buffered visual

EDIT 4:

 prime-select query

returns

 nvidia

EDIT 5:

 glxinfo | grep OpenGL

returns

    Xlib:  extension "GLX" missing on display ":0".
    Xlib:  extension "GLX" missing on display ":0".
    Xlib:  extension "GLX" missing on display ":0".
    Xlib:  extension "GLX" missing on display ":0".
    Xlib:  extension "GLX" missing on display ":0".
    Xlib:  extension "GLX" missing on display ":0".
    Xlib:  extension "GLX" missing on display ":0".
    Error: couldn't find RGB GLX visual or fbconfig
    Xlib:  extension "GLX" missing on display ":0".
    Xlib:  extension "GLX" missing on display ":0".
    Xlib:  extension "GLX" missing on display ":0".
    Xlib:  extension "GLX" missing on display ":0".
    Xlib:  extension "GLX" missing on display ":0".
    Xlib:  extension "GLX" missing on display ":0".
    Xlib:  extension "GLX" missing on display ":0".
    Xlib:  extension "GLX" missing on display ":0".

EDIT 6:

    grep i915 /etc/modprobe.d/*

returns nothing

EDIT 7:

 lspci -knn | grep -EA2 'VGA|3D'

returns

     00:02.0 VGA compatible controller [0300]: Intel Corporation 4th           Gen Core Processor Integrated Graphics Controller [8086:0416] (rev 06)
        Subsystem: ASUSTeK Computer Inc. Device [1043:185d]
     00:03.0 Audio device [0403]: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor HD Audio Controller [8086:0c0c] (rev 06)
     --
     01:00.0 3D controller [0302]: NVIDIA Corporation GM107M [GeForce   GTX 960M] [10de:139b] (rev a2)
        Subsystem: ASUSTeK Computer Inc. Device [1043:185d]
        Kernel driver in use: nvidia

EDIT 8:

    modinfo i915 | grep -i 0416

returns

    alias:          pci:v00008086d00000416sv*sd*bc03sc*i*

Answer 1

You need to fully uninstall the drivers, you installed before and then install them again.

Run in terminal

sudo apt-get purge 'nvidia.*'
sudo apt-get purge bbswitch-dkms
sudo dkms remove bbswitch/0.7 --all
sudo apt-get install nvidia-352 nvidia-prime

then reboot.