Before I can advice you further I need to understand how your problem started. Do you have any other symptoms? How has your mood been lately? What is your line of work? Have you been in shift-work? Do you suffer from any other illness or are you currently on any medications?
You will need to be evaluated for all the above.
Until then I suggest you follow sleep hygiene techniques:
1. Use your bed only for sleep. Ensure it is clean, comfortable with pillows and comfortable sheets.
2. Have a bath at least 1-1.5 hours prior to bed, wear clean comfortable clothes.
3. A tall glass of warm milk, if you are not allergic to it, can help with your sleep.
4. Ensure you have your meals a good 2-3 hours prior to bed time.
5. Avoid coffee, tea or nicotine after 4 pm in the evening.
6. If not accustomed to exercise, try to avoid strenuous exercise in the evening.
7. If you are unable to sleep, don't stay in bed. Get out of the bed and sit in a chair, read a book in slightly dim but adequate light. Don't read on screens. Prefer non-exciting material to read.
8. Try not to preoccupy yourself with thoughts of not being able to sleep. It's fine if can't sleep. It will regularize slowly. Any habit takes time to form.
9. Yoga can help, especially pranayama and shavasana.
If these measures fail, you can further try a formal consult.
Next Steps
Follow sleep hygiene
Health Tips
Shavasana, pranayama techniques