All campaigns have been completed. Auto-translated

I was playing "Heroes of Might and Magic V: Tribes of the East". I got to the last campaign, which is for the mages. There are 4 missions. I completed the first one (where you defeat Zehir with the dark elves), and the second one (where you first play as Zehir, and then as Frida and Duncan). I destroyed the last demon castle, and they told me, "Congratulations, mission completed." Then, the game started loading something, probably another cutscene, and then the power went out... :-( After the power was restored, I launched the game and saw that only the first campaign and the first mission were available, so I had to start playing from the beginning. I loaded the last autosave, defeated the demons again, and they said, "Congratulations, mission completed," and then I was kicked out to the main menu without any consequences, where again only the first campaign and the first mission were available. WHAT SHOULD I DO???

download the save file from the internet...

I had something similar happen to me once (but it was with the first part, and it seemed to be with the elven campaign, when I had to kill Nicholas again). After I completed it the first time, the game crashed, I don't know why, and the mage campaign became unavailable. Even autosaves didn't help (I just kept crashing after all of that). And when I decided to start the mission from the beginning, it wasn't very pleasant, nothing crashed anymore, and I was able to continue the quest calmly.