How to convert a difficult employee into a favorite team player?

Motivation is the only factor which can convert any employee into a dedicated employee. In addition unbaised compensation package will make everyone as a team player. If the line managers are unbiased and transparent in their decision and action team will play with a winning spirit. Most importantly the communication from top to bottom and bottom to must be a true evidence information based direct communication. Too many middle managers in communication will spoil the core message from employee to employer and vice versa... Overall the employee must feel that he is responsible for the company output and must believe that employer will take of him in all the ways....

By motivation about his work and his activities, caring him , listen him , helping him , all these activities can change him and then added to him in its own core team

by motivating them emotionally and give them freedom to express thier opinion

Litsen to him, study him, assess and go through a 'swimming with him' for some time and make a turnaround 

By being friendly to your employee,try to find out what makes difficult make a dialog with him or her.

Act your self like a good leader not like a big boss. Try to convince him/her that his/her contribution to the team is very important, and more important try to him/her that he/she is part of the team.

make him a leader first and he will be as soft as a wool

Be a leader and understand his personality

Always try to understand the expectations of an individual from his boss, here I am not talking about salary increment. There are many other things which could result an individual to become difficult employee. Some employees wants recognising (advertising in side organization), some want appreciate and word of "GOOD JOB" these small thing can really change the attitude of your employee and he/she can become a good team player.