Forgot to sign tax return

[Hopefully_adult]

I think I forgot to sign my tax return, but I have moved out of the place I filed from, so cannot know if IRS returned my mail. What can I do?

[Critter-3]

First put in a change of address with the post office so mail  can be forwarded. 

Next mail in a form 8822 to update your address with the IRS ...  https://www.irs.gov/pub/irs-pdf/f8822.pdf

[Hopefully_adult]

Will IRS resend me the tax refund form (if they have already sent it to my old address), or will this only change the address for anything they send after today?

[Critter-3]

They should resend the return with an address change.  Of course the IRS is taking more than 4 months to process mailed in returns to it probably has not been looked at yet.