Please help me to find an example of his own lack of success in the Death of a Salesman.
Willy's flashbacks in The Death of a Salesman serve as an escape mechanism. He uses these to cope with his own lack of sucess.
A reader does not have to look very hard to find examples of Willy Loman's lack of success. If you examine Willy's roles as a father, husband, and provider, you will find him lacking. First of all, we know that he has failed as father. He and Biff are estranged at the beginning of the play. Biff is a drifter, who at thirty, is still trying to find himself. Happy is only an assistant to the merchandise manager, who finds himself having sex with women who belong to other men. Neither son seems to have much self respect or a firm grip on who they are as individuals. At the end of the play, we see that Willy deeply disappointed the young Biff with his philandering, and that Biff never recovered from the shock of discovering that his father was having an affair with another woman.
Of course, this affair is what makes Willy a failure as a husband. Throughout the play, we hear the woman's laughter--the woman who was Willy's mistress. In the present, we see Willy's irritation with Linda, his constant refusal to allow her to express her opinion or to partake in a conversation with her sons and her husband. At the end of the play, we know why: Willy's affair makes hims feel guilty whenever he is around his wife.
As a provider, Willy never was very successful. Even though he bragged about being a great salesman, we learn through his flashback with Linda that Willy never made very much money. He barely made enough to cover the bills. In the present, he is reduced to working for straight commission and borrowing from Charlie to make ends meet. He dreamed of making it big, like his brother Ben, but he never really did. So, he transferred all his ambitions to Biff, who only disappointed him, as he disappointed Biff.