I took a look and i dont know that you can change the settings without getting into the game first. Did the game ever work and then maybe you changed a setting causing it not to run? If so try doing a fresh install maybe that will put it back to default values.

I think i remember someone saying that you cant go to lower difficulty game after you beat it

I don't think he is talking about difficulty setting. Sounds more like a graphics setting to where he is unable to play. I could be wrong.

Documents\My Games\Runic Games\Torchlight 2

There's a file called local_settings.txt

Make sure to create a backup before you mess about with it though.

Edit: Also mode not supported sounds like the resolution is to high for your screen/tv whatever.

You want to change these:
RES_WIDTH
RES_HEIGHT

to whatever resolution it can support

This post was edited by Civill on Oct 5 2012 10:25am

What display are you using?