Found solution from a book this time.
I did'nt knew books still are useful after google :-)
1. I Created a Script Manager in the master page and referred the scripts in that.
2. Linked css in header of master page.
3. And added function in the content page through a javascript file.
This may help if anybody faces similar issue:
Pls note that positioning of script is very important hence location included.
In master page:
css file link:
<head runat="server">
<link rel="stylesheet" href="~/Scripts/jquery-ui-1.11.1.datepicker/jquery-ui.css" type="text/css"/>
Jquery refer:
<form id="form1" runat="server">
<asp:ScriptManager ID="ScriptManager1" runat="server" EnablePageMethods="true">
<Scripts>
<asp:ScriptReference Path="~/Scripts/jquery-1.11.1.js" />
<asp:ScriptReference Path="~/Scripts/jquery-ui-1.11.1.datepicker/jquery-ui.js" />
</Scripts>
</asp:ScriptManager>
<div id ="pagewrapper">
In content page:
<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">
<script src="../../Scripts/textboxdate.js" type="text/javascript"></script>