Many iPhone users are reporting a issue that while going through messages in selected all of them to just delete them , but instead press report junk by pressing the " report as junk". After this screen popped this messages are reported as junk. Checked block messages and contacts and is none of it is there. All messages where gone from text messaging and no message in received from those numbers. But this is creating trouble for many users as some messages contained important contacts/data. It will be good idea to put delete on top and report junk underneath.
After accidentally sending contact numbers to junk on iMessage and want to find out a solution to retrieve contacts from the junk list in iPhone: Please follow these steps
Step 1: Have a another Apple device with same Apple ID
Step 2: Log into your iMessage onto your 2nd device, when you log into iMessage you should get a code sent to your 2nd device device. Type this code in your 1st device/iPhone.
Step 3: Send the person an iMessage( to contact you sent to junk/spam) on your second device. (When you send it to them on your second device, it will show on your iPhone) after it shows the conversation on your iPhone you can start messaging them again
Hopefully this fix the issue. But by this way you have to do it for each contact one by one.