What's goin on?! please help?

hey guys i got this girls number and we texted for like seven hours last weekend and it was great but recently whenever i texted her she'll respond but then when i send her a second text she won't text me back i'm startin to think she's not interested but at the same time if she wasn't interested why would she text me back why not just ignore the texts? idk guys its just drivin me crazy!