Helloeveryone

function openSearch() {
  document.getElementById("myOverlay").style.display = "block";
}

function closeSearch() {
  document.getElementById("myOverlay").style.display = "none";
}

document.querySelector("#openSearchBtn").addEventListener("click", openSearch);
document.querySelector("#closeSearchBtn").addEventListener("click", closeSearch);

$(document).ready(function() {
  $('#openSearchBtn').click(function() {
    $('#myOverlay').css('display', 'block');
  });

  $('#closeSearchBtn').click(function() {
    $('#myOverlay').css('display', 'none');
  });
});

<button onclick="openSearch()">Открыть поиск</button>
<button onclick="closeSearch()">Закрыть поиск</button>