Messages

Retrieve a deleted message or conversation

In Messages, tap Edit. Tap Show Recently Deleted . Choose the conversations with the messages you want to restore, then tap Recover. Tap Recover Message or Recover [Number] Messages.

Delete and recover messages on your iPhone or iPad

You may get better and prompt responses if you may kindly provide the iPhone Model that you have and the iOS version if it is known to you and re-post.

With the limited information that you have provided, It is hard to even guess the problems faced by you. 

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