Not sleeping

My daughter 18months and she hasn’t sleep through the night at all since she was born. I put her to bed at 10 and she always wakes up at 2am and won’t go back to sleep until 7. I’ve tried everything and nothing working. I don’t even let her nap during the day to sleep if that’ll help her sleep through the night it doesn’t. I take her out to the park and for walks she still wakes up at 2am. I don’t know what to do anymore someone please help.