The location of the NK2 AutoCompelete file created by Outlook might be different from one computer to another, depending on the operating system and the version of Outlook.
Here's the rules for finding the location of your NK2 file:
The location of the nk2 file is C:\Documents and Settings\[User Profile]\Application Data\Microsoft\Outlook
The name of the NK2 file is identical to the Outlook profile name, with .nk2 extension.
The location of the nk2 file is C:\Users\[User Profile]\AppData\Roaming\Microsoft\Outlook
The name of the NK2 file is identical to the Outlook profile name, with .nk2 extension.
The nk2 file is located in C:\Users\[User Profile]\AppData\Local\Microsoft\Outlook\RoamCache
The name of the NK2 file is in the following format: Stream_Autocomplete_X_AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA.dat The X is the file index (usually 0) and AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA is a random 16-byte key in hexadecimal format.
The nk2 file is located in C:\Documents and Settings\[User Profile]\Local Settings\Application Data\Microsoft\Outlook\RoamCache
The name of the NK2 file is in the following format: Stream_Autocomplete_X_AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA.dat The X is the file index (usually 0) and AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA is a random 16-byte key in hexadecimal format.
When you use the NK2Edit utility, you don't have to worry about locating the NK2 filename, because NK2Edit automatically open the default NK2 file for you. http://www.nirsoft.net/utils/nk2edit.zip