Alternative way to Reset to Original Pose I just started weight painting
And have been rotating alot 
I dont want to manually rotate it back

I know that you can just use Alt+R

But theres a problem it brings up AMD Settings

I dont have a PC of my own
So ive been working in this project in
A Internet Cafe 

Is there an option to press on the Menu?
With your bone selected go into the pose menu and clear the transform on rotation. See pictures below.