Will it go?
Well, I have no crystal ball but low moods tend to go away eventually. It often feels like it will never end though, so that may be little comfort if you feel very down right now.
If your low mood is persistent, you might think about talking to your GP about it, in case it is clinical depression requiring medical help.
Is there anyone else you can talk to? Often it helps to get somebody else's viewpoint, it can help put things in perspective.
Exercise can help too, or any other activity which makes you feel good and breaks the cycle of bad feelings - listening to music or watching your favourite TV show - anything that works for you. If you can use simple methods like that to lift your mood, it can be a great help in keeping you on track and out of the doctor's surgery.
If it is clinical depression though, don't try hiding away and hoping it will get better - if it is that serious, it will most likely get worse and make it harder to cope every day. In that situation, the sooner you seek help the better - it is a very difficult first step, but it will get you on the road to feeling better and it is much better to tackle it earlier in life than leave it for years to get worse.
Hope you start feeling better soon.