Who is Saint Jude? 
St. Jude is known as the patron saint of lost causes amongst Roman Catholics. This is due to the tradition that, because his name was similar to the traitor Judas Iscariot, few, if any faithful Christians prayed for his intervention, out of the mistaken belief that they would be praying to Judas Iscariot. As a result, St. Jude was little used, and so became eager to assist any who asked him, to the point of intervening in the most dire of circumstances. The Church also wanted to encourage veneration of this “forgotten” disciple. Therefore the Church maintained that St. Jude would intervene in any lost cause to prove his saintliness and zeal for Christ, and thus St. Jude became the patron of lost causes.
The National Shrine of St. Jude (Chicago USA)
Prayer to Saint Jude: 
O most holy apostle, Saint Jude, faithful servant and friend of Jesus, I honour and invoke you, as the patron of hopeless cases; of times when we feel isolation and despair. Pray for me, I am struggling. I implore you, to bring visible and speedy help to me in this great need, that I may receive peace and consolation in all my necessities, tribulations, and sufferings, particularly [here make your request] and that I may praise God with you and all the Saints of Heaven. I promise, O blessed Jude, to be ever mindful of this great favour; to always honour you as my powerful support.
Amen.