hi,
try to use hidden control when you click the button set the value for that hidden field control like<hidden id="hidImgVal" value="0"> and
then update the value onclick event set ="1" then you can identify the image easily..
<asp:LinkButton id="lnkAssign1" Text="check" CssClass="firstImage" runat="server" Height="35px" __designer:wfdid="w2" OnClientClick="return ChangeImage("0");" CommandArgument='<%# Eval("DriverId") %>' CommandName="Assign" ToolTip="Assign"></asp:LinkButton>
<hidden id="hidImgVal" value = "0"/>
function ChangeImage(iVal)
{
var iValue= iVal;
if(iValue == 0)
{
document.getElementById("imgBtn").src = "images/image1.jpg";
document.getElementById(hidImgVal).value= 1;
}
else
{
document.getElementById("imgBtn").src =images/image2.jpg;
document.getElementById(hidImgVal).value= 0;
}
return false;
}
Cool..
regards,
senthil J