So... Is there any? 'Cause I can't find it, and in the state of a mission I'm in right now, I'm pretty much screwed.

Isn't there a 'suicide' button/function 'thingy' in these games or something like that ? If there is please make sure it'll do what you need/want before using it, ok? I only played D2 for a short while a long time ago and i'm really fuzzy on the details to say the least...

The game SHOULD autosave at the beginning of the mission. Really, there's no way to start over except to reload a previously saved game.
Disciples is kind of unforgiving, so I recommend saving early, often, and in multiple slots.

Actually, it DOES autosave and I have never noticed! It didn't even occur to me to click at 'campaign start' save, 'cause I always thought it's gonna be... Well... Saved start of the campaign. So yeah, I have finally found out how to restart mission. Thanks for the advice, guys :-) Now who do I give rep...