I have a form with a standard reset button coded thusly:
Trouble i
Complementing the accepted answer, if you use SELECT2 plugin, you need to recall select2 script to make changes is all select2 fields:
function resetForm(formId){
$('#'+formId).find('input:text, input:password, input:file, select, select2, textarea').val('');
$('#'+formId).find('input:radio, input:checkbox').removeAttr('checked').removeAttr('selected');
$('.select2').select2();
}