Is depression or a mood disorder always means mental issues? If a parent lost a child and is depress and sad does it mean the parent has mental issues or could the parent have a mood disorder? If it is a mood disorder is it bad? I would say this is a trag

Neurochemical disord. situational depression is a reaction to a traumatizing event. The loss of a child is certainly traumatizing. All mood disorders are bad but there is help available through counseling and if necessary shot term medication.
Losing . Losing a child can be devastating. Grieving is natural in the aftermath of such a loss. This is not something that one is likely to work through very quickly. The loss of your child, changes your life. A person may at times find it hard to believe that their loved one is gone. At other times they may be emotionally numb. Deep feelings of sorrow and anger (even sometimes toward god) may predominate at different times. Although the loss will never be forgotten, in a healthy situation, the parent will eventually find balance in their life again and move forward. How long will the deep grieving last ? - i don't have an answer for that - possibly a couple of years, possibly longer. Each person is different regarding the time if takes them to heal. In behavioral health, we call the grieving process bereavement. Sometimes a bereavement can be complicated by depression. That is when the person just can not get out of their emotional rut and they might find it hard to get out of bed each day. Maybe it is hard for them to find a reason to live without their child. They may sleep too much or too little. They may eat too much or two little. When a person develops depression, it is hard for them to function. Being depressed does not mean that a person is crazy. Being depressed feels bad, so from the aspect of hurting i guess you can say that is not a good thing. Being depressed doesn't make you less of a person, nor does it make you a bad person. A person who has suffered a major loss needs to be kind to themself as they work toward healing. I hope that this helps.
Grief . Grief is a normal reaction to the loss of loved ones. Various societies have various culturally built in mechanisms to deal/cope with the grief. The humans have some built in coping mechanisms to deal with grief. These grief reactions are time limitted ( 6-18 months ). If the person continues to be sad in a persistent manner for a longer period of time the grief reaction enters into a new phase and it then be considered as a mood disorder and this mood disorder requires professional help.
To . To lose someone very dear almost always leads to significant emotional difficulties, the magnitude of which will depend on a variety of factors. To answer your question "does it mean the parent has mental issues", yes..It is a mental issue because it affects your mind. "could the parents have a mood disorder"; i believe this would depend on one's definition of a "disorder". To be depressed-sad about a significant loss is a natural occurrence; i wouldn't consider it a disorder in the greater scheme of that personal experience. I really wouldn't consider it strictly a "disorder" because it is the natural emotional change amongst a majority of us. I would prefer the term "mood change" instead of a mood disorder. I think my replies will also give you an answer to the question "if it is a mood disorder is it bad"?