Oppo
Unarchive a Conversation in Messages auf Oppo
On Oppo phones running ColorOS, the Messages app moves conversations to a separate archive instead of deleting them. This happens when you swipe a chat away or archive it manually to clean up the inbox. The conversation and its history stay intact, but new messages from that contact will not show up on the main chat list until the thread is restored.
To bring a conversation back, open the archive from inside the Messages app.
Tap on Messages ➔ Open the Menu ➔ Tap on Archived ➔ Tap and hold a Conversation ➔ Tap on Unarchive
Once unarchived, the chat reappears on the Messages home screen with its full message history and future texts will trigger normal notifications again.
If a conversation never shows up in the archive either, check whether it was deleted instead of archived, since deleted chats cannot be recovered through this menu.