Updated to OS X Yosemite, everything has deleted So I've already tried to find a solution on Google, but I'm not really good at following some broad IT instructions. 

If you guys could help, that's be more than awesome!

After I installed OS X Yosemite, all my stuff was gone! 

It's like a whole new Mac! 

Meanwhile, I have figured out that my usual stuff is still stored somehow on my Mac, but I don't know how to get it back to being my regular account. 

If I go to Finder > Macintosh HD > Users, there's a folder with all my stuff in my regular account.

Any assistance would be truly appreciated!
Since you can see your "stuff" it is still there but under another user.

Somehow you made a mistake and created a brand new User account with nothing in it so now you have 2 users on your computer each with they separate folders and files.

What you need to do is to log out of that user account (go to Apple icon top left and select log out).

Now you can log in in to your other user account.