Severe insomnia. Have tried everything. Have taken two benadryl and 2 Ambien so far. Still can't sleep. Valerian root and melatonin dont work.

Have you seen a. sleep specialist? In the meantime - how is your sleep hygiene? Retire & rise same time each day. Bedroom should be dark & cool - used only for sex & sleep. Turn off tv. No naps. Exercise regularly but not in late evening. No caffeine for 6 hrs & no alcohol or tobacco w/i 2 hrs of sleep. Dinner should be moderate sized & finished at least 2 to 3 hours before sleep. Can try warm milk, chamomile.
Many sources. Insomnia can be caused by anxiety, depression or anxiety. And, it can also be related to certain medications or substances. Your detailed history and other symptoms would help clarify your underlying condition to form an effective treatment plan.