Waiting on letter from irs

I called and spoke to someone with the IRS she told me I will be receiving a letter and to call them when I get it and have my 1040 because I have to verify who I am which is fine. The question I have is do I need my 1040 from last year because when I try and pull this years up lt downloads something saying I don't have to file (state). Where can I get my 2019 1040? After they verify who I am how long does it take to get my refund? I filed and was accepted on Jan 29th. I'm so confused why am I having to validate who I am? Do they just randomly pick people?  PLEASE HELP