TextBox:Accept Only Numeric,Characters and Integers on KeyPress

HTML Markup:

For Contact Number you can use this code, first add JavaScript and call it onkeypress.

<script type="text/javascript">
    function isNumberKey(evt)
    {
        var charCode = (evt.which) ? evt.which : event.keyCode
        if(charCode > 31 && (charCode < 48 || charCode > 57)) return false;
        return true;
    }
</script>
<asp:Label>Contact No.</Label>
    <asp:TextBox ID="txtClientContact" autocomplete="off" runat="server" onkeypress="return isNumberKey(event)" pattern="\+?\d[\d -]{4,9}\d">
</asp:TextBox>

For Integers values you can use following,first add JavaScript and call on keypress.

<script language="Javascript" type="text/javascript">
    function onlyNos(e, t)
    {
        try
        {
            if(window.event)
            {
                var charCode = window.event.keyCode;
            }
            else if(e)
            {
                var charCode = e.which;
            }
            else
            {
                return true;
            }
            if(charCode > 31 && (charCode < 48 || charCode > 57))
            {
                if(charCode === 46) return true;
                else return false;
            }
            return true;
        }
        catch(err)
        {
            alert(err.Description);
        }
    }
</script>
<asp:TextBox ID="txtAmount" autocomplete="off" runat="server" pattern="^[1-9][\.\d]*(,\d+)?$" onkeypress="return onlyNos(event,this);"></asp:TextBox>

For Email verification you can add pattern in TextBox,

<asp:TextBox ID="txtClientEmail" autocomplete="off" placeholder="Enter Valid Email Id" runat="server" pattern="^\w+([-+.']\w+)*@\w+([-.]\w+)*\.[a-zA-Z]{2,3}$"></asp:TextBox>