> "Anyone knows a script that can select all muted events in selected track or in all tracks?"

Here's one that will select all muted events in a project while deselecting those that may already be selected:
(especially if the next key you press will be delete) ;-)

//*******************************************************************

//*     Program: SelectMutedEvents.cs

//*      Author: John Rofrano

//*     Updated: March 10, 2015

//* Description: Selects all of the muted events and deselects all

//*              non-muted events.

//*------------------------------------------------------------------

//*   Copyright: (c) 2015, John Rofrano, All Rights Reserved

//*******************************************************************

using System;

//using System.Windows.Forms;

using Sony.Vegas;



class EntryPoint

{

    public void FromVegas(Vegas vegas)

    {

        foreach (Track track in vegas.Project.Tracks)

        {

            foreach (TrackEvent trackEvent in track.Events)

            {

                if (trackEvent.Mute)

                {

                    trackEvent.Selected = true;

                }

                else

                {

                    trackEvent.Selected = false;

                }

            }

        }

    }

}

~jr

John Rofrano
Sundance Media Group / VASST
www.vasst.com
www.fasstapps.com