Left a group message - how do I get back on that group message

I had creator of group try to re-add me and they can’t. It won’t allow them. Yesterday I was able to post on the group, but when they responded it came back from individuals and not as the group. Today I can’t even post to it. When I search for the group it pulls up the name, but all the members names are gone. Very frustrating! Any other ideas?

I was finally able to get back on. Someone managed to get me re-added. No one is sure how, but it worked. Thx for responses.