When literally everything in life is giving you a headache and all you want to do is crawl into bed, you know you're having one of those days. Bad days either creep into your life slowly or are triggered by some event that puts you into a bad mood.
Whatever emotions you're feeling, just remember that they are emotions, it's all in your head. That's not supposed to mean what you're feeling isn't valid. You are allowed to have bad days where you feel like being alone and doing nothing for 24 hours straight. Your feelings are valid, but they will go away if you focus on something else.
When you notice yourself slipping into that horrible mood, you can start digging yourself out of it by thinking about all the god things in your life. Whatever makes you happy, hold on to that thought. Your thoughts attract the things that happen to you. If you wish you could make your day go better, stop wishing and start thinking happy thoughts.
There's no other option to get out of your funk than to just snap out of it. Just take a minute to rattle off things in your head that make you happy or that you are grateful to have in your life. You need to actively remove yourself from the negativity that's in your mind, and if you put it there, you can get it out.
Now, there are things that are out of your control that put you into a bad mood. You can't control people or events that suck, but you can control the way you react to them. If you need to take a day or two to hate everything, then do it. But you need to find the strength that you have inside yourself to let it go. You are the only one who can give yourself peace.
I am not a therapist or psychologist. I do not know if you should take my advice, or if it will help you feel better if you do. I know that I've had my fair share of bad days, and while they are always going to pop up from time to time, I can turn them around. These are the realizations I've had. Not only does it feel liberating to be in a good mood for yourself, you will be a light in your friends and family's lives that they may need.