MacBook "messenger" deleted an entire android text thread from my iPhone

I was attempting to send a friend (who uses android) a text with a link via the messenger app on my MacBook Air. I had to type the number as the contact doesn't even show up (none of my non-iphone contacts do). Non-iphone texts never showed up on my macbook Messenger app (don't know why, they just didn't and I didn't bother to look into it). My text ended up not being able to be sent (again, dont know why), so I clicked "x" to delete that particular text on the MacBook Air app. When I did, the entire thread on my iPhone (dating back to June) disappeared. How do I recover this thread? I have OS Mojave, so it's an old os and I can't just select "recently deleted texts" like all the other answers state to do. Any other suggestions? I thought I was backing my messages up on iCloud and it shows I have 18.44 GB of "messages" stored. But I can't retrieve anything. Please help!

Desperate in SF.