Open the start menu and type in:
C:\Users\%username%\AppData\Local\Microsoft\Outlook\RoamCache
The Auto Complete file starts with Stream_Autocomplete and ends in .dat
Finally rename your backup copy, to the one being used by your current Outlook. Then copy and overwrite.
![[nslookup[5].jpg]](http://lh3.ggpht.com/unifyandconquer/SMii3E2SuBI/AAAAAAAAAC8/gHR1BNpjljI/s1600/nslookup%5B5%5D.jpg)