One place to find it is: http://www.securiteam.com/tools/6G00B1F0AS.html
"This utility was originally designed to upgrade the PST
format to version 19. One of its side effects, however,
is that it can strip out the PST password. This can therefore
be used to recover passwords you may have forgotten on
your PST files.
Yes, there are tools available that can easily find the password
in an Outlook PST file. Try a search on google, but be careful about
running any programs that mnay corrupt or change the file.
Or you could just use a standard password recovery service: