If someone is really depressed and having self destructive thoughts and behavior what can i do to help such a person?
Is there a good meditation for such a one?
What kind of advice will it be best for a such a one?
Metta meditation can help as it subdues hatred which is a major cause for suicide. Other Samatha meditations like Anapanasati can help to attain extremely pleasant states of the mind like the Jhanas where there's no depression. Vipassana can be practiced to make one not react to unpleasant feelings or thoughts and eventually achieve lasting peace.
I would try to advise the following:
Meditate on whatever arises in the mind and know that emotions are just transient and they don't really define anyone. If it is depressed mental state, accept it and meditate on it. Whatever you resist will persist.
Be mindful in everyday life and be thankful for all the things one has and may be for the things one doesn't have as well. Enjoy the small little things you encounter, e.g. nice warm sunshine, clean air, clean running water in one's own home.
Ending one's life prematurely or self-mutilating behavior does not change one's karma for the better, that is to say, if they are in a situation with extreme suffering in the present life, they will continue their suffering in their next lifetime as well. So, one can not escape their suffering. Reverend Kusala Bhikshu is fond of saying, "Karma has no eyes, karma has no ears." No matter how much one tries to escape their suffering they will not be able to escape their past deeds.
Suicidal behavior goes against the first precept which is to avoid killing.
A loving kindness (metta) meditation may be useful. This can be done by first wishing happiness for people that are hostile to the meditator. Then wishing happiness for people that are neutral to the meditator, and then finally wishing happiness for those that are close to the meditator(oneself). This is usually done with eyes closed while sitting on the floor or a chair with some kind of timer.
Let him know that by forfeiting early by self disqualification he will reincarnate again in this realm but have a even harder life.To end his suffering he must endure to the end by helping others get through their trials by being a positive force not a negative force, if we all stay positive the ride will go smooth and the next life and realm will be a precious experience.
I myself choose to stay back in the lower harder realms where much suffering and hardship is experienced,helping the weak get through is worth reliving the agony over and over again.