I maked a mistake in the puzzle in fortress of fear, and I don't know how restart it. Someone have a clue? I tried all the morning :\

You can simply switch the levers. You don't need to reset it. For each head/field there is a pair of levers, one switches it on, the other off. Initally all are on, and you have to press the off levers only. If you press an on lever by mistake, simply press the corresponding off lever.

Check this guide for which level does what
https://gamefaqs.gamespot.com/pc/564551-might-and-magic-iii-isles-of-terra/faqs/33301
(Section 5-1-1)

thanks :D

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