Download old Usenet Messages

I am using Thunderbird 140.9 on a Mac Desktop. I use it for reading Usenet (yes I am a dinosaur) and using news.eternal-september.org as the usenet source.

Somehow, I managed to delete all of the messages I could see prior to Feb 26 for one of the newsgroups I read... long story. Is there a way that I could redownload messages for prior to that, say maybe 6 months?

Would the best solution be to delete the newsgroup from the feed and then reenable it? Or would it just start putting in new messages starting the time I reenable the newsgroup? Update: I am reluctant to do this since I might loose what I already have from the last month or so. But also seems like old messages might be disappearing. I do not have any type of message deletion turned on to the best of my knowledge.

Maybe set up another usenet feed? If so, what is a good source?

FURTHER UPDATE AND CLARIFICATION

I don't remember what exactly I did because I was flailing around a lot trying to do something else. And all previously unexpired messages disappeared. Just GONE.