Not a teacher
Another wild guess:
Do you mean "There is nothing to lose"?
Let me give you an example: You have applied for a job, but now you don't know if you should go to the job interview. Maybe you are no longer sure that you want this job. I would say to you: "Go to the interview, there is nothing to lose" or "Go to the interview, you have nothing to lose". This means if you don't go to the interview you won't get the job. If you go to the interview they might offer you the job, but you don't have to take it. So you are in the same situation as before.
So if somebody says to you "You have nothing to lose" it means whether or not you do something you are not worse off than you are now.
I hope this answers your question. If not: Context! Context! Context!
TomUK