All in one PC won't turn on at all

[Little-C]

HP 22-3160na all in one will not turn on. 

I went downstairs to make a coffee, came back, PC dead. First thought was a new power lead after popping the back off and inspecting, ordered one, very disappointed when I ran upstairs all excited.

PWR LED on motherboard blinks once immediately on plugging in new cable, nothing happens with the old one. The light should normally be illuminated the entire time its plugged in, like a stand by light.

Tried reseating everything, checked all cables, to be honest I feel like I'm missing something simple, or I just hope that's it.

It is driving my mad. I need my uni work, I've been staring at it for four days on and off just hoping for a light bulb moment.

Only change from factory is more ram, tried booting without still nothing.

Any help, advice, very very much appreciated.

[WAWood]

@Little-C 

Sorry you got ignored for so long -- so I will provide some comments if you are still working this.

First, I understand about Uni work on a PC, as I did that with all my Graduate and Post-graduate work -- but I had the common sense to do regular backups of that work to external devices.  You should have done the same -- as all PCs fail, it's just a matter of WHEN.

Second, if you follow the instructions below, you should be able to make a bootable USB stick you can then use to boot the PC into a state where you can retrieve the Uni files and copy them off to external medias:

If your PC can not boot into Windows, a way around that is to follow the instructions below to create boot media from Macrium Reflect (MR) that can be used to boot your PC even if the hard drive is not working:
1) Download and install Macrium Reflect (MR) from this link on a working PC: http://www.macrium.com/reflectfree.aspx
2) Use the option to create a boot USB stick or CD

That will create MR bootable media. Then, you can boot your PC into WinPE using that media.

Have patience, as that can take a while to start and bring up the screen.

Once the screen is there, read this thread about using PE Explorer -- a simple file explorer: https://forum.macrium.com/PrintTopic15803.aspx

If your disk still works, you might be then able to retrieve some files and folders from it.

Good Luck