This depends on which version of Windows you are running, and how you have it configured.
TP has a default location where it will create a database on first run, or if it can't find the database specified in the Startup section of Preferences. On my system (Win 7) that is C:\Users\Pete\AppData\Roaming\ThumbsPlus\ and my guess is that is the same as your C:\ProgramData\ThumbsPlus
The other location is your data folder and is probably your live database file. Check the file sizes; the default one will be very small as it should only have the 23 sample pictures in it.