Was in Multisport, didn't record one segment, can I reconstruct it?

If the activity was really not started, then neither the GPS, nor the logging was active, hence there is no hope to recover the part of the track. You can add the missing distance manually, though.

I don't understand why you constantly misread stuff.  Like this is constantly happening in your posts and you still reply.

I made it clear I have the mileage, so why do I care about the gps?  Who said anything about "recovering" something not there?

Can you just stop trying to be so helpful?  I've posted previously where I've caught you seemingly intentionally doubling down on bad information and continuing after you were caught and called out.  Just please stop replying to everything where you don't have the answer.  It's worse than not having an answer at all which you don't.

Yes, sorry, I saw "i have the kilometers lost", and somehow understood from the title that you want to reconstruct the missing activity track, which is as I wrote, not possible without the GPS data, although the known distance can be edited. Not sure what you need, then.

Just stop.  Please.  This is happening constantly.  It's not helpful, it's happening all the time, and I keep asking you to stop, but you won't and I can't understand how you're everywhere on the forum.

OK, so you know the kilometers, you can figure out the Calories, you know the GPS was not logging, so could tell what do you want to reconstruct? And what do you mean by "add it back"?  I won't suggest tapping Edit, and adding the estimated distance and Calories of the 3rd lost segment, to the 1st one, because I guess you'll feel offended by the advice again. But if you formulated your questions clearer, the answers could address it better too.