Did 2020 return but got held up with IDVerify, IRS doesn't show that we filed at all.

I am in an endless loop of a nightmare. I filed my 2020 returns through Credit Karma (an Intuit product) and rec'd the notifications that they had been accepted, both state and federal.  I rec'd a 5071C letter in August 2020.  I misunderstood what they wanted, so it sat for months.  I've gone to Credit Karma to get a copy of the return and am being directed to a page that is asking me to update our income!  That site was a dead end. 

I logged into IRS and according to them, we didn't even file a 2020 return.  The transmittal was blank. 

I screwed up and didn't print my returns for that year because I had a digital copy....until my computer was hacked.  I can't get into the IRS number listed on the 5071C, I keep getting a We are too busy with the high call volume message.  I can't get into the regular # for the IRS because I don't have my AGI nor the amount of the refund.  Should I just file it again?  If I do, they may want interest and penalties.  So much of a nightmare!