How can I find out which IRS my return was sent to ?

Not sure just what you are asking.

Which IRS address?    If you e-filed then  it was not sent to any IRS address - it simply was entered into the IRS e-file system.

If you paper filed then it was sent to the address that you addressed to.

Thank you, I am asking because my injured spouse form didn't go through with Turbotax and I'm trying to do it manually. The letter states to mail the form to the IRS you mailed the originally mailed the tax form. I will send it to my local office and hope for the best.

They want it mailed to the address for paper returns.

Send it to the address in this list for your location.

https://www.irs.gov/filing/where-to-file-paper-tax-returns-with-or-without-a-payment