There are some reasons why Samsung messages are deleted:
1. Factory Reset
2. Accidental Message Deletion
3. Phone Crash
Stop using your Samsung phones until the messages are recovered by an application like Fonedog Data recovery (Android).
Avoid using the phone until the messages have been recovered.
Try to recover deleted messages as soon as possible as the longer the message remains un-recovered the harder it is going to be to recover the file later and the higher the chance that it will be overwritten.
About how to recover deleted messages from Samsung as follow:
Step1: Download and Launch Fonedog Toolkit.
Step2: Connect to your device.
Step3: Select type of files to scan.
Step4: Preview and recover deleted messages from Samsung.
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