can i run symbian 3 games, on nokia 5233 after flashing with latest firmware ?

What do you mean restore original? Flashing your phone with the newest firmware provide by Nokia does that for you.

As for running the apps, if they state clearly that they need Symbian 3 then no, they will not work on your phone. If not, try them.

As long as they don't rely on the GPU that most Symbian^3 phones have, the applications will work on older phones as well.