Different ASL words for different meanings whether you mean "fail to win a game" or "unable to find something".
How to sign "lose", "lost", "loss" in American Sign Language:
Meaning: to become unable to find something or someone.
Related signs: MISPLACE, FORGET, MISLAY.
Meaning: fail to win (a game, contest, competition, etc.). See LOSE as in "be defeated".
First 100 words.
As you feel more comfortable with the first few hundreds of ASL signs, progress further with your vocabulary and learn signing more.