Want to access Messages that may have been deleted

Text Messages were showing up on two iPhones (with the same login), but I wanted Message threads with certain people to show up on only one iPhone. On the iPhone where I did NOT want those Messages to appear, I deleted those specific threads, and turned off iMessage. However, on the phone where I wanted to keep those Messages, I now only see Messages with one specific person since this past Monday, with none of our Messages prior to Monday appearing, including last week. I guess my deletion actions got rid of the Message threads on both phones, which is not what I wanted. I thought deleted Messages would be retained in iCloud forever, as that's the setting on my iPhone. How can I find or access those deleted Messaages, as I'd like to restore and view them to this phone? Thanks in advance.