I have hp laptop and it has windows 8.1 upadated and i have to reset it but some error is coming.

[Saransh2]

Actually i have hp latop pentium and i have upgraded to windows 8.1 and now in my laptop there are many files which i want to delete.So i want to reset it but the error is coming as " Some files are missing.Your windows installation or recovery media will provide these files.

[Atanu4]

How you get this recovery media? Did you created by your own? I think during creation something went wrong and your recovery media is not usable at all now. Can you please provide your laptop model number so that we can have a look specifically for your model.

Now a days OEM has started embedding windows product key in bios itself and if you just install a fresh copy of windows it will activated automatically.  Please check if your laptop has such facilities or not.

The last thing you can do you can order a fresh recovery media from hp.

[Lil_Boy_Blue]

Hi

You have a  --   HP Notebook - 15-ac168tu

https://support.hp.com/gb-en/product/hp-15-ac100-notebook-pc-series/8499326/model/8960682/product-in...

that came with Windows 10?

https://www.microsoft.com/en-us/software-download/windows8iso  is the location of the W8.x iso.

How did you get the OS and a Licence key?

What was the original OS as shipped?

[WAWood]

@Saransh2 

You didn't actually say you used Recovery Media, so I am going to presume you tried to do a reset using F11 or the HP Recovery Manager.  Problem with that is that upgrading the OS corrupts the Recovery Partition -- and that is critical in a reset working properly.  So now, you can not use that method and have to use external media to restore the PC to working condition.