If you are on Windows XP with Outlook 2010, then it's here:
C:\Documents and Settings\Username\Local Settings\Application Data\Microsoft\Outlook\RoamCache
Close Outlook, if it's open. Once you locate this folder you can normally identify your file because it should be larger than 19kb. If that's the case, copy the latest two files to another folder so you have a backup. Then take the smaller file name and rename it to .old and then copy the name of that file (minus the .old) and rename the larger file to exactly the same name. Open outlook give it 15 to 30 seconds to register the file change then open a new email and check to see if it starts populating the emails addresses. If for some reason it clears your file you will need to attempt this again from the backup of the files you took. In some cases, if it didn't work the first time it almost always worked the second time.
See below for the screen shot.
Post Id: 74
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