If it was a needle, you do not know if it was used or how long it had been present on the
beach. Most people, even IV drug users do not have
HIV and
HIV does not survive for long periods of time when outside of the body.
If the injury was due to a needle and if it was contaminated, your risk for infection would be no greater than about 1%. At this time, there is nothing that can be done. You are far beyond the time when preventative therapy would have any benefit.