I am extremely indebted to you for your responses, you have been very very helpful!
That could be worth a try but I'm not familiar with using a VGA cable - I've only ever used laptops.
The only way I could assimilate your problem would be to disable my Intel graphics which I'm loathe to do should I just end up with a black screen and not be able to get back in.
Switching on and powering down should be done consecutively while Windows is starting to see if you get the Automated Repair screen.
Do that twice and the Automated Repair screen should come up when you switch on the third time.
You may have to repeat that process and power shut down three times for the Automated Repair screen to come up when you switch on the 4th time.
It does it after power shutting down just twice for me.
If you get that screen it will go onto diagnosing your pc then attempting repairs which can take a while.
The machine eventually booted Windows but I'm not sure what you will get with not having any main graphics.
I don't know what you are using to post on but if you have access to another computer, you could create a Hiren's Boot disk to see if that can find a way to boot up with your onboard VGA graphics.
https://www.techspot.com/downloads/6966-hirens-bootcd.html
Use the 15.2 download button.
I bought a VGA cable to see if I can see the Automated Repair screen in a secondary monitor (HDMI doesn't work but VGA maybe does).
I'm also trying to get a monitor or TV that has VGA input, since from the laptop screen I keep seeing everything in flashing black.
I will try Hiren's BootCD PE on a usb drive right away! I have an old laptop from 2012 that is extremely slow but I can use it for these tasks. I hope the tool will work, although I have a doubt that the BIOS gives priority to the hard disk and I can't select the USB priority (not seeing anything on the screen).
So you know, repairing the Microsoft Store would not affect your computer display. It's a coincidence that while fixing one thing, another broke, sadly not rare. The Windows Store fix is a well-documented registry change that's been used for years.
OK, next up. Once you have no screen or display, you have a problem, a BIG problem. That's why the repair shop sent it back.
The only option is to find a way to see the screen and use System Restore or reinstall. I suspect your display card, hardware, or the screen itself has died, so let's check that out:
Boot using ANY boot CD, bootable Linux, or thumb drive. You could even boot off a Windows ISO or try the key combination to access your computer's restore program (if it has one).
If you STILL can't see your screen, you've eliminated Windows, and its settings as the problem and now know you have a hardware issue. By the way, any good shop should have done this for you.
I don't think it's the fault of your tool either. I have used it in the past with satisfaction, I think there was some software or hardware problem that with the procedure maybe aggravated.
I'll also try a Windows or Linux bootable (unfortunately via USB, my laptop doesn't have a CD drive), though I think the problem will still be there.
Oh, that's easier. Reset the BIOS to factory settings. Step 2, using the jumpers:
http://www.majorgeeks.com/content/page/how_to_reset_your_bios_to_optimaldefault_or_factory_settings.html
I already tried step 1. I'm sure when I press F2 I enter the BIOS because when I press this key the screen goes black(off, no backlight) for a second. Then I pressed F9 key to automatically load factory settings, then pressed enter to confirm, F10 key to start Windows, then pressed enter to confirm and after all that I see the screen turn off again for a second. And I guess it started Windows then.
But it didn't work, still can't see anything on screen.
So I gotta go with step 2. I've already opened the PC and I'm sure I don't have the flat battery (CMOS), I've also looked up disassembly guides for my laptop and even there they say it's not there.
I'll try with the pins, maybe I'll find some video guide that will explain how to do it.
And thank you again very very very much!!!