Sound becomes distorted after changing channel requiring pushing mute button and back to sound again to restore proper sound

Hi,
Use the mute button to turn sound off
& then mute again turn sound back on

didn't press the mute button did you
if not then the sound board has failed
take it in for a proper diagnosis and quote

Mute Switch/Mute-Clip LED :

• This switch mutes all Aux, Group and L/R sends from the corresponding channel.
• This switch is equipped with a red LED that will illuminate when the channel is muted.
• When the MUTE button is out,the LED functions as a Clip indicator that will illuminate at 2 dB below clipping.
• Muting the channel does not prevent the PFL signal from being sent to the PFL/AFL mix when the PFL Switch (12) is in.
• This switch mutes its respective Group send from the Group channel.

Go to page 11 in this link :
Peavey FX Mixer Series Operating Manual

You can also try, Restoring Factory Settings, in the Utility Menu Options.
Go to page 16 in ths link :
Peavey FX Mixer Series Operating Manual

CAUTION:
Restoring the factory settings option resets your mixer's presets, reformatting factory presets and erasing all other user presets. (This option is handy when your venue has permanently changed and all-new presets are required.)
Once confirmed, the presets are not retrievable and will be permanently lost.
Should you select this option in error, a warning screen allows you to cancel the procedure.

Try hitting the mute button twice.

There is a conflict between the data card and your sound system or it may require shared files that current sound system uses, there for muting it out so full access is acquired.

Does the distortion ALSO appear when you listen with headphones? If not, the problem may be downstream. The driver for the mute control line to the mute transistors may have a problem. Make sure the mute is off.

Push the MUTE button on the TV remote to restore audio.

Does it show that the device is working properly in the device manager? You could try and use system restore to roll back windows to a time when the sound was working. Windows may have updated software and caused problem with audio. If you roll back the system to a time when you know the sound was working then the on board audio may be defective. Have you tried plugging in headphones in the headphone jack and check if there is sound? Are the sound properties muted? The laptop speakers or internal amp may have stopped working also.

I had this same problem this morning. Luckily, when I reset the whole thing and did the channel search again the sound returned. I have no idea why it fixed it but it did. Hope this helps you.

Only the right channel had a sound,the left channel is mute, whatever adjustment you did and whatever balancing you done nothigs happen,even you interchange the speakers. The problem is in the power amp. The STK IC there is busted already, it's better to change it with a new one so the performance become normal again.