To inset back button in your WordPress page, paste below PHP code and CSS code

PHP Code

<script>// <![CDATA[ 
  function goBack() { window.history.back() } 
  // ]]></script> 
<span class="button" onclick="goBack()">Go Back</span>

CSS Code

.button		{
  background-color: #ddb502;
  border: 1px solid #ddb502;
  color: #ffffff;
  padding: 10px 16px;
  border-radius: 0px!important;
  cursor: pointer;
}
.button:hover	{
  background-color: #c6a202;
  border: 1px solid #c6a202;
  color: #ffffff;
}