...
function switchvisibility(elem){
	alert(getElementById(elem));
	if (el.style.display == "none"){
		el.style.display = "block";
	} else {
		el.style.display = "none";
	}
}
</script>

</head>
...

<form id="formuploadimage" action="">
<table>  <tr>    <td colSpan="2">Load drawing<br>      (here you are allowed only to upload svg file format) we recommend max. 2 Mb:</td>  </tr>  <tr>    <td >        <input type="hidden" value="da" name="sefacetata"><input type="file" value="D:\kitfree\POZE FAMILIE\petro\sent.jpg" name="poza_x">    </td>  </tr>  <tr>    <td>      <input id="button" type="submit" value="Upload">    </td>  </tr></table>
</form>

<table class="alternatingtables"><tr><td>
<span class="alert">Current drawing : </span></td></tr><tr><td>
<span class="info">
<a href="#" onclick="switchvisibility('tree')">dwgF</a>
</span>
</td></tr>
</table>