How do you handle lazy & unreliable colleague? How do you approach him/her in a positive way?

Approaching a lazy colleague is never an easy task, but for me the best way is to ask hep from that person in a nice manner, you could start by saying " Excuse me could you help me with these, our head asked me to do it but I really need you help." Asking for help is the first step, then as time passes by if he/she still refuses to work you can approach and tell that person how you feel but not in an offensive way.