Always make sure of noting down your tracking number if you want to get updates. However, once you lost the tracking number, you cannot obviously track your courier. There is only one way to do that, and that is by tracking your tracking number.
You may be able to find that number if you are the one who shipped the package, and you did it through the USPS website. If you did, you may have received an email confirmation of the shipment that included the tracking number. Also, if you created a login to the USPS site at that time, you may be able to log in and find your shipment history which is pretty user-friendly.
On the other hand, there is a way to tackle this problem but the answer still depends on some factors. Attempt to get back your tracking number from the seller or sender. Now, if you are the sender.
Log on to the Courier Official Website
Most couriers nowadays support multiple ways to track a package. For example, Eurodis supports four ways to track a package. They are Eurodis tracking by 24 digits barcode number, 13-digit EURODIS shipment number (often called as tracking number), shipper´s reference and dispatch partner´s shipment number.
Proceed with a Call to the Local Post Office Customer Service
Try to contact your local post office customer service and provide as much and detailed shipping info as you can. They have records in their recording system and there are chances of finding yours.
Retrieve From Social Media
If you tracked your package on TrackingMore and shared it via social media, you can retrieve your tracking number through the link you shared. Or click that link directly to check the tracking info of your package.