2 screens but my PC only detects one!!!

Good evening,

Your computer only detects one screen because you have connected it with a single cable.
Connect both screens to different ports (DVI, VGA, HDMI...) on your graphics card and both screens will be recognized!

--
Knowledge is acquired through experience; everything else is just information.

Let's go back, tell us how you connected your 2 screens.

Do you have a desktop PC? If so, what model?

Your cable is not good,
It simply allows you to duplicate the display,
If your PC didn't come with a special cable and only has one video port, you need a special box like a triple head.
Sincerely

Have you installed the NVIDIA driver?

Are your two screens exactly the same?

To summarize, if there's only one port coming out of your graphics card, and your cable is (what we call) a Y-cable, meaning it has one connector on one end and splits into two on the other end, then you'll have the same image on both screens and you won't be able to do anything about it... You need one port per screen, and generally two screens per graphics card...

My computer only has one port to connect a screen... so I’ll have to have another one added if I understand correctly?? Is there really no other option??
Thank you

I have Nvidia and my 2 screens are exactly identical!!
And when I duplicate, only one works, extended doesn't do anything!!
Seriously, I'm lost!!! Thank you for your help and if you have any other solutions... I would be happy to hear them!!

There is a VGA port and a DVI port on your graphics card if I'm not mistaken...

So you connect one monitor via DVI and the other via VGA... And if your monitors don't have a DVI and/or VGA port, adapters are available.

Knowledge is acquired through experience, everything else is just information.

I connected my 2 screens with an adapter and what do you mean by a desktop PC?? :S

Yes, it's a desktop PC, and I tried Windows + P and selected Extend, but I can only see both of my screens turned off and they turn back on but are still in sync!!!

Finally someone who has the same problem as me <3. More seriously, I only have one VGA port on my PC. So I bought a kind of VGA splitter (http://www.fnac.com/mp14803679/MHP-Le-Cable-VGA-de-repartiteur-de-15-epingles-1x-HD15-Male-2x-HD15-Repartiteur-d-Y-de-Moniteur-de-TFT-DE-tube-cathodique-Femelle-Avance-de-Cable/w-4). After carefully making all the connections, I turn on my PC, and then, disaster strikes:
My screen had cloned onto the second one :'(

After a lot of research online, I decided to ask you for help

I hope you will help me...
THANK YOU :)

I don't quite understand your connections...

But go take a look at: control panel -> display -> connect to a video projector.

From there you can configure your screens (duplicate, one only on, extend...).

What kind of adapter is it?

By desktop PC, I meant "desktop computer" (not portable).