You could always try to roll back to a previous restore point - seee this article:
http://windows.microsoft.com/en-gb/windows-10/windows-10-recovery-options
If you have not dpne anything that creates a restore point the simplest expedient would probably be to use the media installation tool and create the appropriate install media; either a CD or a USB stick.
Make sure you make a note of the Windows product key
http://windows.microsoft.com/en-us/windows-10/product-key-windows-10.
Install media can be created using the media creation tool you will find at the bottom of this age:
https://www.microsoft.com/en-gb/software-download/windows10
Here's a few more notes:
http://winsupersite.com/windows-10/windows-10-clean-install-using-media-creation-tool#slide-0-field_images-57241
USB Media creation notes here:
http://www.thewindowsclub.com/how-to-create-bootable-usb-media-from-iso-for-windows-10
Once you are up and running, make sure you create a backup
Loads of info out there. All you have to do is search FOR YOURSELF
February 2016
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