DS did this alot. He didn't STTN until he turned three, and then still up 3-4 nights. I would take him to bed and lay down with him until he fell asleep. When that was easier, I took him back to bed, laid down for 5 minutes and left, then 4 minutes, then 3...etc. In addition to that, I started a sticker chart and in the morning he got a sticker if he stayed in bed til green light. When he collected 5, we went to Chuck E Cheese (he picked the destination). Then his new chart needed 10. Then his new chart needed 10 consecutive nights- so he started over if he didn't make it.
ETA- I found if he seemed fearful, I'd change his gears by taking him to the potty, having him pee, then giving him a sip of water. And that helped reset his mood.