Monitor not receiving signal from VGA

[AllHailPuppy]

My partner just received two HP Compaq LA236X dual modules today to go with his PC tower. He can't get even one to display the screen it keeps coming up that the VGA is not connected and then the monitor goes to sleep mode. The PC tower works with TVs and HDMI cables however, the monitors do not have any HDMI ports. Any help would be very appreciated. 

[Prométhée]

Hello
I might not be of much help, but you do not give enough information
to start, can you confirm or not, I only find this model, not the reference you give:

HP Compaq LA2306x 23-inch WLED Backlit LCD Monitor Product Specifications

so if this is it, in fact it is indicated
VGA (analog)
DVI-D and DisplayPort w / HDCP

You also indicate:
The PC tower works with TVs and HDMI cables however, the monitors do not have any HDMI
but we finally do not know which computer is this, it has at least hdmi, but nothing else ??
If there is only hdmi, you will need special adapters in order to work in VGA, and everything is not always suitable!
I have never tested, but I know that some hmi / vga cables are not correct
It is the same for the other ports

[AllHailPuppy]

Yes, it is basically the one in the link my partner does not know where to find the module or brand of the tower, he says it is a mixture of different parts. The tower has a VGA, HDMI,  and DVI. 

[AllHailPuppy]

Probably no help sorry  but here is a picture of the back 

[Prométhée]

It’s not obvious,
maybe he knows the exact model of the graphics card installed?
from what I see here, the tower has a graphics card at the bottom!
you have obviously removed a cover where you can clearly see the vga port!
the latter cannot work if a graphics card is connected in general!
I distinguish a port dvi, but I do not know the type if it is the same as indicated for the screen you need the right

cable and connect it here!

DVI-D

DVI Connections
next to the red / pink cable is HDMI, it is connected to a tv, is that it?

[AllHailPuppy]

We obviously didn't remove any cover that's how it came like.  Two friends already solved the problem  now very fast with only the information given, I guess YouTubers are more of the experts on this matter 😂 Thanks anyway. 

[Prométhée]

sorry, but i think i gave the answer to the question, namely to use the correct port / cable ..
if you have not removed the cover, it is possible that in the original configuration there was no graphics card, and that a screen was connected to the motherboard directly

Now if you have solved your problem it would be much better to share than to make up your mind, right?