Win10, Mouse and Kb not working in Windows - works in BIOS screens

The fix for this problem might be available somewhere in this Forum.
I had a look around but have not come across it.
On Win10, my son's desktop has all of a sudden stopped recognising the mosue and keyboard.
They work within the BIOS screens which tells me it is a Win 10 bug.
I have gone into recovery screens and there the mouse and kb also work.
I have removed kb and mouse drivers that were not windows (at some stage my son had a razer mouse and a kb, so I removed those drivers through command prompt
Problem not resolved.
Reloaded Win10 - booted all the way through to the sign on screen but KB and Mouse still not working
Did it again - Went all the way through to the sign on screen and got message You do not have Administrator permission or something to that effect. Tried a few suggestions, like going into the Reg files and changing the admin reg file but that made it worse because after doing this I could not get into any screen in recovery mode because of "No administartor defined" or something to this effect.
Have now reloaded Win 10 the third time. This was was a complete new install, removing all files and apps, etc.
Boots all te way to the sign on screen but thel KB and Mouse still do not work..
I am thinking that this might be malware which is somewhere deep in the HD mening that I might have to reformat the hard drive.
Is this the correct approach or is this maybe a known problem, and I am missing something someone else might have already resolved without reformatting the HD?
Your help highly appreciated.
Regards.
R

hi
Thanks for your reply.

They are USB

2/3 years old, not sure of the Asus model

"Have a look at the Device Manager. Do the devices necessary for whatever sort of keyboard and mouse you have have drivers installed? Are there any yellow triangles present?"
Cant get into windows.
Devices have always worked fine, though. Tried other mouse and keyboard, generic Microsoft, also don't work

"A clean install of Windows is to unallocated space on the drive, booting from a Win 10 installation medium.
It would have involved deleting existing Windows partitions - note usually plural (4 for a UEFI installation, less for MBR).

Is that what you did? "

No, it went online and reloaded

Do you mean you used one of these options?

Clean Install Windows 10 - I used this one

If you have a live boot disk, boot the PC from that and check the devices work. - Don't have one, unfortunately

If you don't have mouse and keyboard under windows, how do you navigate to open device manager etc?

On BIOS, do you have Fast BOOT? Is it enabled?

dalchina
Try post #83 on here:
Keyboard and mouse not recognized after boot-up!
In that thread there's also reference to a particular update that caused this problem- but with an older build.
Keyboard and mouse not recognized after boot-up!
post #41

Thanks for the help. Looked at these but didn't help.
In the end reformatted disk, partitioned it and reinstalled, I was just not getting anywhere fast.
Problem solved but still not sure what caused it.
Thanks again for the support, much appreciated!.
Regards.