I accidentally put the wrong mailing address in by one number and haven’t received my refund. How do I fix this

First see if your refund has been mailed to you.  

Check the Where's My Refund site.

Cpntact the IRS and ask for help with correcting your address.  If the check was mailed to the wrong address, you can have them track the mailing, find out if the check was cashed, and ask them how to proceed.

Following the steps on this Get Human page has gotten me to an agent the quickest.  The key is not putting in your social security number when asked.  That confuses the phone system and sends you to an agent.  

I call at 8:00 AM in my time zone and usually wait about 20 minutes.

File a form 8822  ASAP ...  https://www.irs.gov/pub/irs-pdf/f8822.pdf

and alert your mail carrier of the mistake ... they may be able to intercept this for you.