Driver updates are here- Support for Inspiron 7459 | Drivers & Downloads | Dell US

Are you up to date? 

I'm sure I've done this a lot and every time all devices are recognized except for the NVIDIA GeForce 940M graphics card

That hardware info doesn't look weird...

Are you saying there's no NVidia card listed in Device Manager but an "Unknown" device is listed? In this case, right-click and Uninstall that Unknown device.

Then click Action>Scan for hardware changes on the Device Manager toolbar. See if the NVidia card (or an unknown) appears nows.

If the NVidia appears, shut Windows down normally and reboot. Is it working properly now?

The graphics card appears in the device manager as 3D Video Controller
And when I try to install drivers, either from the nvidia website or from the Dell website, the following message appears
NVIDIA Installer cannot continue
I tried many and many ways, but to no avail. When I searched on the Internet, I found some ways that the problem is that the graphics card ID is not integrated with the drivers. When I applied to a YouTube video, I skipped the first error, but the installation did not complete, some attempts were made in a program, the installation completed and the graphics card appeared in the device manager with the name NVIDIA GeForce 940M, but it does not work, it just looks fake, but during My attempt, I noticed that there is no problem with the tariffs, but because the device number is in the tariffs, which is
PCI \ VEN_10DE & DEV_1347
The previous code is in all the drivers I tried to install, but if I go to the NVIDIA graphics card details from the device manager, I find that the graphics card ID is
PCI \ VEN_10DE & DEV_1347 & SUBSYS_00000000
While the code in the definitions is the following
PCI \ VEN_10DE & DEV_1347 & SUBSYS_06EF1028
If we notice the difference between them, we find the difference in the last part, which is
SUBSYS_00000000
SUBSYS_06EF1028
So I felt that there is a problem with the graphics card, which is that it does not contain these numbers 06EF1028 and instead of these numbers we find 00000000
I hope someone can help me or tell me that this problem has no solution until I stop trying to solve this problem
Sorry for my writing style, unfortunately I don't speak English and I'm using Google Translate for this discussion

Did you delete any Unknown devices listed in Device Manager?

You may have to click View>Show hidden on Device Manager's toolbar first. Then look everywhere in Device Manager, not just under display adapters.

When was last time you replaced the motherboard battery? If the battery is weak, the settings might be corrupted and BIOS isn't seeing the 940M correctly.

Or, it's possible it failed. Unfortunately, it's attached to the motherboard and probably can't be replaced without replacing the motherboard.

I did not delete an unknown device in the device manager and there are no hidden devices

I haven't changed the motherboard battery in a while, but I don't think it has a problem because the device keeps dates even inside BIOS

I think there is no solution to this problem and the graphics card is damaged

@ProSky.EG  You didn't delete any Unknown, but do you see any Unknown listed?

The PC will automatically update date/time via the internet, so you may never know if it's being corrected because the battery is weak. Might be worthwhile replacing it since it's probably old, even if just to rule it out as a problem. 

If the NVidia graphics card is damaged, but Intel Graphics are working, you could just keep using the PC.