If you have a brand name laptop (and some brands of PC) then you are probably quietly confident that in case of catastrophy you can always restore to factory default.
This is not necessarily true!
If you have succumbed to (or been tricked into) the Windows 10 upgrade, you have almost certainly lost your "get out of gaol free card"
If your PC or Laptop has a recovery image, there may still be a way of creating recovery disks. You may remember seeing a notification all those years ago when you first started your brand new PC which asked if you wanted to create a set of recovery CD's. Look in the programs list for the manufacturer name, somewhere there you will hopefully be able to find "create recovery disks", possibly, as is the case with Dell, under backup and restore.
You will need at least 2, but possibly 5 blank DVD's and a lot of patience.
Once complete, put them in a safe place. You will need them in case of hard disk failure or system catastrophy.
Whilst Windows 10 preserves the recovery partition for such events, it preserves it's own version of the recovery. ie. it creates a recovery that may well include problems created by the upgrade to windows 10 (as was the case for Fred - who after hours of recovery had the same issue he was trying to repair). Even if the recovery image is perfect, it will be of no value if you cannot run windows, or if the hard disk has failed.
The only good news is that even if Windows has created it's own recovery image, the software provided by HP, Lenovo, Asus, etc may create disks from the original image (at least that was the case with a recent HP laptop which thankfully created a Windows 8 install which was easily upgraded to 10).
Fred is now happy that all is well, but for an extended period it did not look like the problem was going to end well at all.
If you can create a set of Recovery Disks - please do so.