http://track-chinapost.com/result_china.php?order_no=LY157256655CN shows No shipping record. This means your seller applied this tracking number from china post but never actually ship anything to you. You are very likely to be scammed.

if you just got this number, You should push seller to ship the goods immediately. Tell him if you can not track real shipment data in next 3 days, you will open dispute to aliexpress/amazon/ebay/paypal against fraud.