desktop environment is not working

What version did you upgrade from, please and what method did you use?
Do you use proprietary video drivers?

 it was 16.4
Method was software updater
proprietary video drivers, I have no clue on that one.

Uninstall the video drivers then boot to the OS and reinstall them. It is rare for proprietary video drivers to work after a release upgrade

Uninstall the video drivers. Do I do that through the synaptic Package manager?
I see I have mesa-vdpau-drivers when I looked it up video drivers on it.

boot to OS? Is that at the start where I sigh in, where I picked Unity?

You can use root recovery console from GRUB and run:

mount -o remount,rw /

You can then uninstall the nvidia drivers using apt

I need this in simple english.
 root recovery console from GRUB ?? I have no clue what that means or is.

what is apt?

and what happen to the boot OS thing? you said.

And you can’t use the internet to find out? Nobody is born knowing it....

Hold SHiFT at boot and select advanced options then select recovery mode

I did and all I got is more computer speak. Still don't know what a GRUB is or what apt is?

ok now you're telling me "Hold SHiFT at boot and select advanced options then select recovery mode"
What does that do?

Then what? What happen to all the other steps you said I need to to do? You're getting me complete lost on what to do and when. Is it really that hard to enplane in order of the what to do and when?

After read a bunch of posts about this problem. Uninstall the video drivers then reinstalling them is not helping anyone in solving this problem. Some people have done it 3 times lol if it will not work the first time it will not work the 2ed or 3ed time. 12 different posts with 12 different answers. Ugh!

Are you just guessing and copying what you have read at the top of other pages without looking to see if it works or refusing to emplane?

You can use root recovery console from GRUB and run:
mount -o remount,rw /
You can then uninstall the nvidia drivers using apt
then I ask a qoestion and you write.
Hold SHiFT at boot and select advanced options then select recovery mode
 ? explaining nothing. how is this help?

what stands out is you wrote "Nobody is born knowing it...."
Unless you can explain it. I get you are the nobody and you don't know either.

When you press the power button to turn on the system immediately hold the SHIFT key. The SHIFT key is on the keyboard. You use it to type a capital letter when you type. If you hold this down the GRUB will load.

GRUB is the boot loader in Ubuntu and makes the OS boot. It has options. Use the cursor keys (The ones with little arrows on) to move the selection to "Advanced Options" and hit ENTER. ENTER is the large in the middle on the right of the largest bank of keys on the keyboard.

Once there, use the same cursor key / ENTER key method to select a line that says "Recovery"

You will now see some text but just wait until another menu pops up and select "root" using the same cursor key / ENTER method as before.

You now have a "root console"

Yes you will see pages with "Computer speak" on them. You are fixing a computer!!

With regards to me not knowing
https://wiki.ubuntu.com/ActionParsnip
https://launchpad.net/ubuntu/+topcontributors

Nar........... try again

Did it a few times, still black.