Levonorgestrel
"If you're here reading this reviews, I'm sure you're freaking out just like I was, I was actually here reading these exact reviews about a day ago. But, I'll echo what many say here, this pill definitely works. Girlfriend got her period last night, and I've been ecstatic since;  I promised myself I'd post here if it came through. People make mistakes, this pill is amazingly good at fixing them. If you're within 24 hours when you take it, you have nothing to worry about, stress will only make your period delay more!"