First, try to get the 1099-R. Often they can be found online, or contact the administrator to get a copy.
Once you confirm that you can't get the form. You can prepare a substitute 1099-R. Enter the information for a 1099-R as best you can.
Wages & Income
IRA, 401(k), Pension Plan Withdrawals (1099-R)
Did you get a 1099-R in 2021? Yes
Get ready to be impressed - Continue
Select Change how I enter my form
Type it Myself
Continue the interview from here.
In most cases, Box 7 is code 7
There will be a question Do any of these situations apply to you?
Select I need to file a substitute 1099-R
Continue through the interview