OK, that was a little harsh. Sorry about that.
But listen, the truth is, the girl (especially if shes hot) probably gave her numbers out to a bunch of different guys last night (girls do that.) So saying, "Hi this is..."does not mean that she is going to remember you. And if she doesnt remember you, she wont reply!
A better way would be to say something that will get herback into that head space that she was in when she met you. Something like...
"Wow, do you remember that fight last night? Im still laughing my ass off. - Henry"
This is not 18th century England. So dont send her messages like...
"Dear Stacey, Im really glad we had a chance to talk last night and I had a very pleasant time..."
Instead as yourself how you would talk to your friends. Think of how you would talk to your own friend. Would you tease them and crack jokes if they did somethingstupid?. (The obvious exception would be if she is foreign or is highly educated and is turned by bad grammar and slang.)
Instead of saying something like, "Hows your day going?", you could say something like...
"Wow, I just had the craziest day. I dont think you can top it. Hows yours going?"