Implement Numeric TextBox validation without using JavaScript and jQuery in ASP.Net

Hi tripurarijha1...,

Use RegularExpressionValidator.

HTML

<asp:TextBox ID="TextBox1" runat="server" />
<asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server" ControlToValidate="TextBox1"
    ForeColor="Red" ValidationExpression="[0-9]*$" ErrorMessage="*Only Numbers Allowed." />

Screenshot