It doesn't sound like the problem, but check that you don't have a filter set - click 'Clear'.
Re-installing PT3 doesn't affect your databases at all, and re-installing the same version of PostgreSQL shouldn't either, as long as you didn't delete the Data folder.
Did you re-install the same PostgreSQL version, and keep your database, as described in
How to reinstall PostgreSQL?
Did you make a backup of your database before you re-installed, or even export your hand histories?
If you did either of those you'll be able to restore/re-import them.