If you have lost someone's username on Snapchat and have no way of contacting them, it can be challenging to re-add them. However, there are a few methods you can try:

1. Search for their username using mutual friends: If you have any mutual friends on Snapchat, you can try asking them if they know the username of the person you want to re-add. They might be able to provide you with the username or help you reconnect with the person [1].

2. Check other social media platforms: If the person has shared their Snapchat username on other social media platforms, such as Instagram or Twitter, you can search for their username there. This can help you find their Snapchat account and re-add them [1].

3. Use Snapchat's "Quick Add" feature: Snapchat has a feature called "Quick Add" that suggests friends based on mutual connections and other factors. You can access this feature by tapping on the "Add Friends" icon on the top right side of the screen and selecting "Quick Add." It may suggest the person you are looking for, even if you don't have their username [2].

4. Try using Snapcode: If you have a photo of the person's Snapcode, you can use it to search for their profile on Snapchat. To do this, go to Snapchat, tap on the "Add Friends" icon in the upper right-hand corner, tap on the ghost icon on the right side of the search bar, and select the image from your photo gallery that contains the Snapcode. Snapchat will scan the code and add the person to your friend list if it matches their profile [2].

It's important to note that these methods may not always be successful, especially if you have no way of contacting the person or obtaining their username. In such cases, it may be challenging to re-add them on Snapchat.

Learn more:

1. How to re-add someone on Snapchat if I lost their username ...
2. How To Find Deleted Friends on Snapchat - Tech Junkie
3. How Do I Retrieve Deleted Friends From Snapchat And Is There Some Sort Of History List? | by TechMintle | Passionate About Tech & Programing | TechMintle | Medium