How do I restore all of. my deleted messages. "ALL OF THEM"?

If you’re using messages in iCloud, you cannot. Deletions are immediate and permanent (see -> Use Messages in iCloud - Apple Support).

If you don’t use messages in iCloud, you will need an iCloud or iTunes backup from a time point that includes ALL of your messages. You would then restore that backup, which will replace EVERYTHING on the device with the contents of the backup, rolling it back to what was there at the time of the backup.