I accidentally changed the default UI Material. How can I change it back?

[choldax]

While trying to highlight an object, using one of the solutions in this question, I accidentally changed Default UI Material. Now, my game looks like below.

For every GameObject, The Default UI Material looks like this

I think I have messed up the shader accidentally. How can I change it back?

[PoorSkill]

Try to reset the Material @choldax