At time prayers are not accepted. At such times one method of acceptance of prayers is requesting a pious person to pray for you, and praying to God, the Almighty to accept the prayers of that pious person...
Once Bawa Ghulam Farid fell ill and prayed, but did not see any improvement in his health. Then he asked one of his disciples to pray for him. His disciple (perhaps Sheikh Nizam-ud-Din (rta) or Khawaja Qutb-ud-Din (rta), who was a very noble and pious individual, prayed fervently but there was no change. Upon this, Bawa Fareed prayed passionately one night: ‘O God! Grant the highest degree of acceptance of prayers to my disciple so that his prayers are accepted by You.’
In the morning, he told his disciple about his prayer. On hearing this, his disciple developed great sympathy and thought in his heart, ‘As he has prayed for me in this manner, so let me start praying for him.’ He prayed so earnestly and with such vigour that Bawa Ghulam Fareed fully recovered.
(Malfuzat, Vol. 9, p. 234)