Open the File > Maintain Database Names window. Double-click on the name field of the database that is marked as the "Dflt" and then it will open a window to tell you the file size and name of the file associated with that db. What are those?
In this folder, C:\Archivos de programa\Poker Tracker V2, is there a file called ptrack_backup.mdb?
If so, with PT closed, rename the ptrack.mdb file to ptrack_bad.mdb and then rename the backup file to ptrack.mdb and see if you can open the program again then.