It's been over 20 years since I survived a traumatic brain injury which included an initial impact to my frontal lobe above my right eye. Since then my emotions have been a bit scrambled, I haven't felt things as intensely as I did before, and I have had extended periods of disinterest in things like my dolls which are major components of my life.
These can be seen as symptoms of depression, I took them as depression, and got upset with myself that I wasn't "getting better". I have had deeper times of sadness that might have been true depression, life circumstances and other things that would get anyone, and I would go on and start to feel better again, to a point.
Recently I read a book called The Tale of the Dueling Neurosurgeons by Sam Keen and learned my spells of disinterest and scrambled emotions are most likely related to the brain injury. It can improve and has but I can let up on myself when I don't have any rat's asses to give about anything. It's a hardware issue. I feel relieved that in a way there's nothing I "should" be doing to "feel better". It also helps me make sense that I'm going back to things from before the TBI that excited me because I'm wanting to feel that again.
If you are feeling sad, mad, bad about life don't go through it alone. If you feel that you need or want help seek it out. I'm still here because I did.