Need historical address information
This is only possible if you have "detailed logging" enabled.  If not, you'll need to restore a backup copy of your database (to a test server!) and do a comparison.

You can check to see if you have detailed logging enabled at Administer menu » System Settings » Misc, under Logging (see screenshot).  If you do NOT have this enabled, please read the logging documentation before enabling it.  If you have shared hosting, you may not be allowed to turn this on; if you run CiviCRM on your own server or VPS, then you should have no problem.


If you DO have detailed logging enabled:


Go to the contact record with the changed address.
Click the Change Log tab.
Find the change that corresponds to the date that the address was changed and click Update next to it.
You should see before-and-after results.