@ RomoLampkin wrote about the 2020 return: "I went back to the IRS's website, and they now have no record of my filing. "
Since you have filed your 2021 return, the IRS "Where's My Refund" tool will no longer display info about a 2020 return; it will now only display info for your filed 2021 return. If you have an IRS account (or wish to enroll for such), you can look at your 2020 "Record of Account" Transcript. You may not be able to deduce much from it, but it would be evidence that they have your return and are working on it, and it should reflect the payments you made toward the 2020 return. If you check it occasionally, you may at some point notice a new transaction code indicating another step has been taken with your return.
I would try to phone the IRS, but as you mentioned, the IRS is not easy to reach. I've reached them a couple of times, and I realize this is anecdotal, but I have found that for me it was best to call just before closing time--about 6:50-6:55 PM and go through the steps that @ Critter-3 outlined above. I figured a lot of folks would not call that close to closing, and that if I was one of the last to get into the queue, they would finish off all the people who were in the queue at closing time. I still had to wait about 25-30 minutes.
If you end up phoning the IRS Taxpayer Advocate Service, they are especially prone to help if you are having an economic hardship or have encountered significant delays from the IRS. If they can't/won't help you, ask them if they will transfer you to an IRS agent. A couple of users have said that, at least for them, that was a backdoor route to an IRS agent.
