windows 10 1709 has changed my default user profile

The update seems to have installed fine, except, my default desktop and user folders don't open like they used to. It seems that the update has created a new user profile and is using that one instead of my old one!

My original folders were under:

This PC/Users/Mark but it now defaults to This PC/ Users/Mark.MY-LIFE

Can someone PLEASE explain to me, in very simple terms, how to to get all my desktop icons and folders back without having to search for them all the time?

Thanks for any help.

Thanks Brink. You're a life saver. Very much appreciated :)
Can I now safely delete that profile?

Checked and dumped!! :) Thanks again Brink.

brink, I just wanted to thank you very very VERY much indeed for your wonderfully clear instructions for fixing a user profile.

Having spent well over a day trying to sort the problem out on my home pc last month (i.e. my user profile having been replaced by a new one following a Windows 10 update) - including hours on chat with Microsoft 'support' and a lot of tearing of hair, etc - I was extremely dismayed to find on Tuesday that the office computer had suffered from the same fate.

So great good fortune indeed that I came across this thread plus the tutorial link!

It was a nerve-racking business, as I'm not particularly tech-savvy, but the clarity of your instructions enabled me to edit the registry and - thank god - things are finally back to normal.

Now just need to persevere with the ongoing problem of why the brand new office Logitech webcam refuses to work on this machine! :)