18.04 - Unmet dependencies error while removing NVIDIA drivers/files

System information:

Ubuntu 18.04 LTS
ACER E5-573G
NVIDIA GeForce 940M

I am trying to download nvidia drivers, CUDA toolkit and cudnn files to use tensorflow with the GPU.

I managed to download CUDA toolkit and nvidia drivers through some tutorials.

I downloaded the drivers directly from the nvidia website and the file name is 'NVIDIA-Linux-x86_64-390.87.run'. To download CUDA toolkit, since on the nvidia website it is only available for Ubuntu 17.10 and 16.04, I used some command to download and install the toolkit(which unfortunately I don't remember but it downloaded 9.1 version).

Then using chmod +x NVIDIA-Linux-x86_64-390.87.run, I made it an executable and then using ./NVIDIA-Linux-x86_64-390.87.run I tried to install it! But it somehow finished the installation process with some error message in between saying 'pre-installation failed!do you wish to continue?' I continued anyways.

Now when I logged back in after I write in my credentials, the screen froze so I used https://askubuntu.com/a/1030490 to solve the error.

But the problem is when I tried running 'nvidia-settings', it says 'ERROR: Unable to find display on any available system'.

Knowing that I made a mess, I tried purging all the nvidia files but it says

$ sudo apt-get purge nvidia-390 (the command I wrote into terminal)

Reading package lists ...Done
Buildig dependency tree
Reading state information..Done
You might want to run 'apt --fix-broken install' to correct these.

The following packages have unmet dependencies:
libnvidia-ifr1-390 : Depends: libnvidia-gl-390 but it is not going to 

be installed
libnvidia-ifr1-390:i386 : Depends: libnvidia-gl-390(=390.87- 
0ubuntu0~gpu18.04.1) but it is not going to be installed.
Recommends: Depends: libnvidia-gl-390(=390.87-0ubuntu0~gpu18.04.1) but 
it is not going to be installed.
E: Unmet dependencies. Try 'apt --fix-broken install' with no packages 
(or specify a solution.)

When I run apt --fix-broken install, it again says some version mismatch and unmet dependency error!

It is really frustrating! Please help me solve this issue. Can I not uninstall every nvidia file and start from start?

Thanks :)

PS: Also I am using Ubuntu Wayland in Login as the normal Ubuntu either zooms up the display to a much lower resolution or freezes the screen!

I reinstalled Ubuntu 18.04 and followed the below two awesome links and Tensorflow GPU got installed like a charm!!!

https://medium.com/@Oysiyl/install-tensorflow-1-8-0-with-gpu-from-source-on-ubuntu-18-04-bionic-beaver-35cfa9df3600

http://www.python36.com/how-to-install-tensorflow-gpu-with-cuda-9-2-for-python-on-ubuntu/2/