fixing sleep schedule

engage in activities that will exhaust you. if they don't work, take meds

I would try some melatonin gummies! Melatonin is basically your brains sleepy chemical, so taking the gummies should make you tired. 

You should also try exercising during the afternoon/evening, and you should try not to look at any screens as much as possible about an hour or two before bed.

If all else fails, you should talk to a doctor( if you can). You might have insomnia, which they can give you meds to treat!

I do not recommend taking supplements or medication, as your issue is not metabolic in nature. 

Your current issue is "Circadian Rhythm" 
A circadian rhythm is a natural, internal process that regulates the sleep-wake cycle and repeats every 24 hours. It is influenced by environmental cues, such as light and temperature, but is governed by the body's internal clock located in the suprachiasmatic nucleus of the hypothalamus in the brain. It's a natural oscillation that repeats every 24 hours. This natural cycle affects all aspects of the human body; mental, physical, and behavioral that the body experiences within this 24-hour cycle. Your brain controls this rhythm, and if it's out of a natural state of homeostasis (state of balance in the body systems to survive and function properly), you won't be able to effectively function day to day, and it will impede your body functions causing an array of disturbances. 

Best way to indicate if your Circadian Rhythm is off:
"Upon waking up to begin your day, the body should naturally feel energized. In the case where a person feels lethargic or foggy, this is an indication the rhythm is off." 

Without appropriate regulation of the rhythm and homeostasis, a variety of conditions will arise such as chronic fatigue, sleep dysfunctions, mood irregularities, etc.. If not corrected and managed in the long run, may form into a disorder. 

Disorders occur when no treatment has taken place, exasterbating current issues that lead to chronic (long-term) side effects, that eventually create a criteria for a disorder diagnosis.