Here are some examples:
* Estou perdido. (I am lost.)
* Ele se perdeu na floresta. (He got lost in the forest.)
* A chave está perdida. (The key is lost.)
Note:
* "Perdido" can also be used figuratively to describe someone who is confused or overwhelmed. For example, you could say "Estou perdido com tantas opções" (I'm lost with so many options).
* In some contexts, you could also use desorientado (disoriented) or desgarrado (separated, detached).
The best choice will depend on the specific situation and the nuance you want to convey.