Atlast found my solution,
This post may useful for future Developers,....
As i mentioned above in my Question, my page is not postback to assign the text values to the sever.
Let me clear myself once again,
"CAUSING POSTBACK ONLY MAKES THE CONTROLS TO RETAIN THEIR VALUES"
<asp:TextBox ID="txt_prodname" runat="server" Width="110px" onblur="dopost();"
In my dopost(), i have added my script as below
__doPostBack was an inbuilt function of ASPX page. For more info, refer