Hi YacharuP,
It is getting displayed normal checkbox after the page is postbacked in updatepanel which means the page gets partially postback and the checkboxe looses all its attributes which you have assigned so you need to use "bootstrapToggle" plugin for applying toggle functionality to the checkbox and maintain the functionality after page postback and you can achieve it like below and for more details on plugin events and options refer below link
Bootstrap Toggle
Refer below sample code and modify the code according to your need.
HTML
<div>
<div>
<asp:ScriptManager ID="ScriptManager1" runat="server" />
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<input type="checkbox" id="msgtoggle" runat="server" tabindex="19" checked="checked" />
<asp:Button ID="Button1" Text="Submit" runat="server" />
</ContentTemplate>
</asp:UpdatePanel>
</div>
<div>
<style type="text/css">
.toggle.ios, .toggle-on.ios, .toggle-off.ios
{
border-radius: 20px;
width: 110px;
}
.toggle.ios .toggle-handle
{
border-radius: 20px;
width: 40px;
}
</style>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<script type="text/javascript" src="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" />
<script type="text/javascript" src="https://gitcdn.github.io/bootstrap-toggle/2.2.2/js/bootstrap-toggle.min.js"></script>
<link href="https://gitcdn.github.io/bootstrap-toggle/2.2.2/css/bootstrap-toggle.min.css"
rel="stylesheet" />
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css" />
<script type="text/javascript">
function ApplyToggle() {
$('[id*=msgtoggle]').bootstrapToggle({
on: '<i class="fa fa-paper-plane-o"/> Send',
off: '<i class="fa fa-ban"/> Dont send',
onstyle: 'success',
offstyle: 'danger'
});
}
$(function () {
ApplyToggle()
});
function pageLoad(sender, args) {
ApplyToggle()
}
</script>
</div>
</div>
