If I understand correctly you inadvertently did something simple that caused you to no longer be able to hear the channel you want to hear.
If so, it's most likely that you hit the button that is 1 up from the botton on the right side (L/Out). This is a temporary lockout. I commonly use it to temporarily lock out the gibberish from any channel that is running encrypted.
If that is what you did a simple power cycle will get your channel back. That lockout works for the duration of that session and is cleared if you turn the receiver off and back on.