"He didn't get lost."

Translation: Il ne s'est pas perdu.

[Mb.A]

I checked so many sources to see if the verb "perdre " goes to the Passé composé
with "etre" but i did not found any thing. is it using "etre" in here because of the change in the meaning which here is "getting lost"and not "losing"?
if i wanted to make the Passé composé of "Quand il est stressé, il perd quelque chose " would that be "Quand il etait stressé,il A PERDU quelque chose" instead of"il EST PERDU quelque chose"

[Lucien660983]

Yes. "To get lost" translates as "se perdre", which is "pronominal" or "réfléchi", and all such verbs use the "être" auxiliary. "To lose something" translates as "perdre quelque chose" and uses "avoir".

[Mb.A]

Thank you sooo much for your great reply.
to help the others with the same question i'll add an example that i just found on Duolingo:
"Je te prête mes lunettes de soleil parce que tu AS PERDU les tiennes."
meaning:"I'm lending you my sunglasses because you lost yours."