http://track-chinapost.com/startairmail.php shows LY040678104CN was shipped from China to USA on April 2 . It was sent to Chengdu airport on April 12. It is still in the airport waiting for flight space to USA.

Coronavirus has cancelled more than 90% airline space to USA. China Post has serious shipping space shortage. So some delay is normal, no need worry. Please wait one or two more weeks to see what will happen.

After parcel arrives USA, USPS website will show arrival info.

If your buyer protection is expiring, you might need to open dispute to claim your money back first. After you get the parcel in future, then pay back to seller.