If you did not use some type of tracking service then you will not know if the tax return was ever received by the IRS.
Use this IRS website for the status of an amended federal tax return, Form 1040X - https://www.irs.gov/filing/wheres-my-amended-return
What year did you amend? That would be too early to amend 2019. Was you first original return Accepted?
After 3 weeks you should have been able to track it here,