Should I file a 2nd amended Federal Return if I filed by mail on 3/4/2020 and the IRS website says they have no info/status (like they never received it). Lost possibly?

The IRS has not processed paper filed tax return for several months due to the pandemic.

Go to this IRS website for information - https://www.irs.gov/newsroom/irs-operations-during-covid-19-mission-critical-functions-continue

 

We’re experiencing delays in processing paper tax returns due to limited staffing. If you already filed a paper return, we will process it in the order we received it.

Do not file a second tax return or contact the IRS about the status of your return.

 

IRS website for the status of a mailed federal amended tax return - https://www.irs.gov/filing/wheres-my-amended-return

According to the IRS more than 10 MILLION pieces of mail accumulated while they were shut down so that will take some time to open and process all those envelopes and then the contents ... patience will be needed by all during this unusual time.