"When the mind doesn't cooperate to repeat a mantra in that case what is the alternate to do so that we are peaceful and not think about that situation?"
Satsangha or association with the wise is ever the best way out...why?
Here are some excerpts from The Gospel of Sri Ramakrishna:
1.The Master looked at the householder devotees seated around him and said with a smile: "Why shouldn't it be possible for a householder to give his mind to God? But the truth is that he no longer has his mind with him. If he had it, then he could certainly offer it to God. But, alas, the mind has been mortgaged-mortgaged to 'woman and gold'. So it is necessary for him constantly to live in the company of holy men. When, he gets back his own mind, then he can devote it to spiritual practice; but first it is necessary to live constantly with the guru, wait on him, and enjoy the company of spiritual people. Either he should think of God in solitude day and night, or he should live with holy men. The mind left to itself gradually dries up. Take a jar of water, for instance. If the jar is set aside, the water dries up little by little. But that will not happen if the jar is kept immersed in the Ganges."
2.Prayer and holy company & Earnest longing
MASTER: "Prayer and the company of holy men. You cannot get rid of an ailment without the help of a physician. But it is not enough to be in the company of religious people only for a day. You should constantly seek it, for the disease has become chronic. Again, you can't understand the pulse rightly unless you live with a physician. Moving with him constantly, you learn to distinguish between the pulse of phlegm and the pulse of bile."
DEVOTEE: "What is the good of holy company?"
MASTER: "It begets yearning for God. It begets love of God. Nothing whatsoever is achieved in spiritual life without yearning. By constant living in the company of holy men, the soul becomes restless for God. This yearning is like the state of mind of a man who has someone ill in the family. His mind is in a state of perpetual restlessness, thinking how the sick person may be cured. Or again, one should feel a yearning for God like the yearning of a man who has lost his job and is wandering from one office to another in search of work. If he is rejected at a certain place which has no vacancy, he goes there again the next day and inquires, 'Is there an vacancy today?'
"There is another way: earnestly praying to God. God is our very own. We should say to Him: 'O God, what is Thy nature? Reveal Thyself to me. Thou must show Thyself to me; for why else hast Thou created me?' Some Sikh devotees once said to me, 'God is full of compassion.' I said: 'But why should we call Him compassionate? He is our Creator. What is there to be wondered at if He is kind to us? Parents bring up their children. Do you call that an act of kindness? They must act that way.' Therefore we should force our demands on God. He is our Father and Mother, isn't He? If the son demands his patrimony and gives up food and drink in order to enforce his demand, then the parents hand his share over to him three years before the legal time. Or when the child demands some pice from his mother, and says over and over again: 'Mother, give me a couple of pice. I beg you on my knees!' - then the mother, seeing his earnestness, and unable to bear it any more, tosses the money to him.
"There is another benefit from holy company. It helps one cultivate discrimination between the Real and the unreal. God alone is the Real, that is to say, the Eternal Substance, and the world is unreal, that is to say, transitory. As soon as a man finds his mind wandering away to the unreal, he should apply discrimination. The moment an elephant stretches out its trunk to eat a plantain-tree in a neighbour's garden, it gets a blow from the iron goad of the driver."