As mentioned you may have selected an empty layer or maybe you selected
a mix that does not have any send levels turned up.
On the right hand side of the mixer what blue button has a light turned on?
On the lower left row of buttons what one is selected?
Not knowing how the mixer is set up and configured it’s tough to guess why the right
side of the sound system is out.
What do you hear if you plug head phones into the mixer?
Was both sides of the system working till someone pressed a button on the mixer?
It could very well be something else in the system has caused the problem with the
right side speaker system.
Let me know if you need my address for the cookies!