Самый простой вариант:
$(document).ready(function() {
$('.menu-trigger').click(function() {
$('.menu').slideDown(500);
$('.contacts').slideUp(0);
});//end slide toggle
$(window).resize(function() {
if ( $(window).width() > 500 ) {
$('.menu').removeAttr('style');
}
});//end resize
});//end ready
$(document).ready(function() {
$('.menu-trigger2').click(function() {
$('.contacts').slideDown(500);
$('.menu').slideUp(0);
});//end slide toggle
$(window).resize(function() {
if ( $(window).width() > 500 ) {
$('.contacts').removeAttr('style');
}
});//end resize
});//end ready