You can search for an address you have been to before by going to Web Portal > CRM > Contacts > Locations.
If you still cannot find the location, then there is a chance that it or the Contact connected to it has been archived. You can search this by clicking on the 'View Archived' selection in the smart table. And if it is there, then you can select the checkbox beside the location and at the bottom of the screen, select the 'Make Active' option.
With the Locations table using the Smart Table format now, you can also filter searches and select what columns you would like viewed when you are sorting through Locations, and then you can save that View so that it remains in the preferred list format that you've chosen.
