Coping with the loss of a parent is simply one of the greatest hardships any of us will face. However with the right support and by allowing oneself to feel the grief, the loss of a parent can be endured, and healing can begin.
Undoubtedly, one of the most intensely difficult experiences anyone will go through in life is the death of a parent. At any age, the loss of a parent is demanding on our ability to endure, although for different reasons. The ability to cope with such a loss depends on the survivor’s circumstances, developmental stage and the nature of the loss.
Effects on children
Young children are profoundly impacted by the death of a parent, as they are entirely dependent on parents to provide them with all their needs. The negative effects of the loss may last well into adulthood, especially if the grieving process was never completed in childhood.
Children pass through developmental stages, therefore their reaction to and ability to cope with the loss of a parent is related to their age at the time of the parent’s death. Additionally, the circumstances surrounding the death play a factor in how children react. They will adjust to the death with more difficulty if it is sudden, if they lack a good support system, if there are immediate stresses related to the death (such as a change in financial status) and if they are already generally prone to maladjustment. 
Between the ages of 3-5, children have not yet grasped the concept of death, therefore they believe that the parent has gone away for a while and will come back. It is at this age that children are most impacted by the loss and at greatest risk for developing psychological problems. From ages 5 to 9, children still have not fully developed an understanding of death and it is not until the age of 9- 10 that children comprehend that it is permanent. 
Children need age specific support and therapy to endure the loss and adults who assume the caretaker role must immediately step in to provide what the child needs. The new caretaker should be sure to allow children to openly express their feelings and understand that they may grieve for years. After a caretaker has been established in the child’s life, therapy should be applied and an adjustment of the child’s concept of self and new relationships should be established. 
The effect of a parental death on teenagers is a little harder to identify, as teens have many complex issues occurring in their lives already. They do report feeling the loss of the parent in their lives, but generally have developed coping strategies at this stage of development. Grieving teens may mask or hide emotions, or they might act out, which may include risk-taking behaviors or loss of interest in school. How adolescents deal with the loss of a parent depends on several factors including the behavior of the surviving parent, which can overwhelm to the teen. Involvement of their social circle of friends is also extremely important to the grieving process, as is a well-balanced personality. 
Effects on Adults
Adults are better prepared to bear the brunt of the death of a parent than are children because they have typically formed bonds within their own family nucleus or have become self-sufficient to a point that they are no longer dependent on their parents. That is not to say that adults are not strongly influenced by the death of a parent, however.
In most relationships, parents are still providers of moral support and companionship to adult children. It is natural to feel the burden of the loss and go through the stages of grieving, which are generally denial, anger, bargaining, depression and acceptance. Grieving may be compounded by what is occurring in the adults life at the time, as well. If the adult is experiencing illness or a divorce, the feelings of grief will certainly be compounded. Significant life events such as birthdays, weddings or the birth of a child will be times when an adult will feel even greater loss.
If the adult child was the caregiver to an ill parent, both feelings of guilt and relief when the parent dies can be expected. When watching a parent age, become ill and go through the process of dying, adults are reminded of their own aging process and increased awareness of mortality, increasing feelings of stress and anxiety. In addition, adults may suddenly be put into the new role of the family patriarch, supplying new pressures. Conversely, if the adult child was estranged from the dying parent, there may be feelings of unfinished business, a sense of incompletion and regret, but also possibly of freedom if the relationship was particularly abusive. 
At this age, the involvement of the grieving adult’s partner and family is especially important as they are necessary to provide not only comfort but logistical support as well, such as errand running and simply helping them to re-engage in life if they are starting to show signs of neglecting their obligations. 
The death of a parent at any age may be extraordinarily difficult. For young children, however, it is absolutely vital that adults step in and take the place of the deceased parent. For children of any age, it is up to all involved in the person's life to help them grieve, endure and ultimately to go on.
 [http://www.allpsychologycareers.com/topics/loss-of-a-parent.html ]
 [“Loss of a Parent By Death: Determining Sudden Impact” Rachel Coyne, Tammi Ohmstede Beckman International Journal of Psychology: A Biopsychosocial Approach 2012 pp. 111-112.
 [“Children and Parental Death: Effects and School-Based Interventions” Loni A. Smith. 2009 http://www2.uwstout.edu/content/lib/thesis/2009/2009smithl.pdf ]
 [Loss of a Parent http://www.allpsychologycareers.com/topics/loss-of-a-parent.html]
[“Parental death during childhood and adult depression: Some additional data” Geoffrey Nelson. 1982, Volume 17, Issue 1, pp 37-42. http://link.springer.com/article/10.1007%2FBF00583891#page-1 ]
[“Death of Parents and Adult Psychological and Physical Well-Being: A Prospective”. Nadine F. Marks, Heyjung Jun, and Jieun Song. 2009. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2638056/]