I would say if you haven't tired the OTC stuff to start there. Most of the OTC stuff is usually Benadryl, or a combo of Benadryl and Tylenol or Motrin.
If that doesn't work, then adding in a melatonin can help.
You also need to make sure you have cleaned up all your sleep habits.
Develop a night time routine, have a set bedtime, no naps during the day. No sleeping for more than 10 hours at any given time. Use a sound machine or sleep app on your phone, or a box fan, some sort of white noise. Make sure you have good pillows, that room is nice and cool.
Once you have done all that and sleep is still elusive there are several options for sleep aids.
1. Traditional sleeping pills, things like ambien, lunesta, and old school stuff like restoril.
2. Low dose antidepressants - these can be very helpful to improve sleep if you have things like migraines or IBS, because they help keep those things in check too, most common one is Elavil, or amitriptyline.
3. Benzo's - antianxiety meds. Low dose Xanax, and Ativan can be great sleep aids. This is actually what I took when my world fell apart. I still take low dose Ativan for sleep when I have trouble. It works well, and has no hangover.
I am reluctant to take Ambien or Lunesta because I have seen the crazy stuff people do on it, and I find it frightening. I don't like to be out of control, and sleep sex,sleep eating, and so forth, yah I don't need that.
If you are leary of taking anything and it's a whole tablet, break it in half, and make sure that you don't have to be up early, or have commitments the next morning. In case you are tired or hungover.
Not sleeping is awful. I hope you find success.