I need help in restoring deleted messages

Go to:

Settings > Your Name > iCloud, etc

Tap iCloud

Are Messages Turned on (green)?

If yes, the messages are gone and cannot be restored

If no, AND you have a backup made from before the messages were deleted, you can restore your phone from that backup. BUT, your phone will be restored to the date the backup was made, so messages sent or received after the backup was made will be gone.