I didn’t answer the second half of the question.
If you can pinpoint why you are depressed, like there has been a big change in your life that would be difficult for anyone, sad for anyone, but you are usually not depressed, and you are not suicidal, just want to feel better, probably as that situation improves you will come out of your depression, so the best thing in my mind is to fake it til you make it, and continue to drag yourself out of bed every morning, do your routine, and focus on the good. Tell a trusted friend what is bothering you so you can talk it through, or write down what is bothering you. However, sometimes once down in that pit of depression, it can be difficult to get back out, don’t feel badly that you can’t snap out of it, that is very common. Talk therapy can be a big help, I would suggest seeing a counselor if you cannot talk to someone in your family or group of friends.
If your symptoms have an anxiety component, that can be more difficult in my opinion, and you might need medication for a time to function.
For me the most difficult depression to figure out was during a time of loneliness, I didn’t really know what was going on. There was nothing obvious to me, or my family. No one had died, I wasn’t sick, things seemed pretty normal from the outside. I was young, and my friends were into other things as we got older. What fixedit for me was getting a job. The new people I met, and feeling good about the work helped me.
The most intense depression I had was after a break-up with a boyfriend, actually I had very bad anxiety with it, which was the worst part for me. My friends pulled together and spent time with me, let me tell them how sad I was, told me stories of how they had been through a similar thing. It helped. I was so anxious I went on anti-anxiety medication for abou 6 weeks to function, to be able to eat, and not shake for seemingly no reason. Eventually, took several months, I began to feel better. The fog really lifted once I moved to FL. It was a new chapter for me.
Here is a great story from an episode of West Wing:
This guy’s walking down a street when he falls in a hole. The walls are so steep, he can’t get out. A doctor passes by, and the guy shouts up, “Hey you, can you help me out?” The doctor writes a prescription, throws it down in the hole and moves on. Then a priest comes along, and the guy shouts up “Father, I’m down in this hole, can you help me out?” The priest writes out a prayer, throws it down in the hole and moves on. Then a friend walks by. “Hey Joe, it’s me, can you help me out?” And the friend jumps in the hole. Our guy says, “Are you stupid? Now we’re both down here.” The friend says, “Yeah, but I’ve been down here before, and I know the way out.”
I think that story applies most with accute, very difficult, depression. That story is not to discourage you from seeing a professional, because a good therapist should know the way out also.