imagebutton2.attributes.add("onmousedown","changeimage()");in html
<script languange="javascript">
function changeimage()
{
document.all['imagebutton2'].src='要替换的IMAGE的路径'
}
</script>
<script languange="javascript">
function changeimage()
{
document.all['imagebutton2'].src='要替换的IMAGE的路径'
}
</script>
ImageButton2.Attributes.Add("onmousedown","bmp\\enter1.jpg");
function changeimage()
{
document.all['ImageButton2'].src='bmp\enter1.jpg'
}