lost

If you are lost you do not know where you are. You might not know how to get home.

Example: I was lost in the woods for a week.

If something is lost you do not know where it is.

Example: My phone is lost.

If something is lost it is gone. It might not exist any more.

Example: All my hope is lost.

If something is lost it has failed.

Example: Trying to reach her is a lost cause.

The past tense of lose.

Example: I lost my phone at work.