Need help finding good 2D learning sources

I'm looking for well explained 2D learning sources on C#. I already tried googling "unity 2d tutorials". I tried doing tutorials (list below), I'd not deny that I learned a bit, but most of them doesn't explain the code behavior so you end don't knowing how you get that far in the project, you just know that "this class tells the camera to follow the player" and "this snippet creates an imaginary line that have something to do with walls". I wanted to read books but I have no money to pay them.

http://anwell.me/articles/unity3d-flappy-bird/ this teached me the bit I know
http://code.tutsplus.com/tutorials/...with-unity-and-the-dolby-audio-api--cms-20863

http://www.raywenderlich.com/70344/unity-2d-tutorial-physics-and-screen-sizes
And a some more I can't find the link.
EDIT: I don't care about the subject of the "sources", I just want to learn stuff like making an inventory, handling through scenes, make a menu (options,quit,etc), saving/loading, physics stuff like bounciness (on a platformer), handling multiple levels, score, win/lose states, parallaxing, etc...

 

I would look here:
http://unity3d.com/learn

There are two main sections:
http://unity3d.com/learn/live-training
http://unity3d.com/learn/tutorials/modules

There is a 2D section in the modules:
http://unity3d.com/learn/tutorials/modules/beginner/2d

There are several 2D sessions archived in the Live Training Archive:
http://unity3d.com/learn/tutorials/modules/live-training-archive

Including:
http://unity3d.com/learn/tutorials/modules/beginner/live-training-archive/2d-catch-game-pt1 (look for additional parts)
http://unity3d.com/learn/tutorials/...raining-archive/making-angry-birds-style-game (look for additional parts)
http://unity3d.com/learn/tutorials/modules/beginner/live-training-archive/2d-scrolling-backgrounds
http://unity3d.com/learn/tutorials/modules/beginner/live-training-archive/top-down-2d
http://unity3d.com/learn/tutorials/...training-archive/introduction-to-unity-via-2d
http://unity3d.com/learn/tutorials/modules/beginner/live-training-archive/infinite-runner

 

Please be aware that most, if not all, of these subjects have nothing to do with 2D.

These subjects are basic or intermediate game development subjects and will be found not by looking for 2D, nor for 3D, but by researching these subjects independently. Physics has both 2D and 3D versions, but the basic concepts are the same. Menus, saving/loading, inventories are all independent of the "type" of game.

 

Thank you !