Okay. Lemme explain how I do that thing >< 

First, I download something, and then the file cannot be open. So that I click the file and then I

select OPEN WITH 

And I try to choose OTHER PROGRAMS.

After that, I select WINDOWS PHOTO VIEWER. 

I want to change it BACK but I dunno how!! T^T

Because I try to download other files but I cant open because of that MISTAKE.

Hope you can help me as soon as possible. Please?