After you file

Thanks so much

Yes it was the contribution for me. I'm not sure it was filed or not. The tax form of that year was a draft and it only contained my ex's 8606. I never got a definite answer from my ex when asked So I just assumed the worse that mine was not filed. 

Would it be a problem if it was actually filed? then re-send would be a duplicate. But I rather safe than sorry.

And yes, for the contributions I made for 2020-21, I filed with correct basic of 2009 contribution. 

Do I just need to send the form 8606 and a letter of explanation?

As I don't have any document except for the 1099-R form and a letter from my brokerage that listed in/out transactions of my IRA. The agent had to track down their database to find since they did  not keep records past 10 years.