After spending good time on internet.i'm finally done it.
var point = new L.Point(-12307.601047734, 6711475.1283642);
var earthRadius = 6378137;
var latlng = L.Projection.SphericalMercator.unproject(
point.divideBy(earthRadius));
new L.Marker([latlng.lat, latlng.lng], {bounceOnAdd: true}).addTo(map);