Huawei
Restore Archived Conversations auf Huawei
When a chat vanishes from the main Messages list without any deletion notice, it usually landed in the Archive instead of being removed. EMUI moves conversations there after certain settings changes, or because you archived it yourself and forgot about it.
Archived threads keep their full message history and attachments. They simply sit outside the default inbox view, which means new messages from that contact can also stop showing up as clear unread badges until you unarchive the thread again.
Bring the conversation back
Open Messages ➔ open the menu ➔ tap Archived ➔ tap and hold the conversation you want back ➔ tap Unarchive. The chat reappears in the main list right away, with every previous message and attachment intact.
If the contact still does not show up after unarchiving, check whether the thread was also blocked or filed under a separate spam category. Archiving and blocking work independently inside Messages.