yesterday i contact customer service online then she said 24hours ago can purchased but alrd 24 hours ago still cant how can i do？

You can't do anything to enable your account. Contact iTunes Support for assistance. See the Apple Support articles below for contact information.   

iTunes Support – world wide 

Apple Support schedule phone call      

If necessary, try Twitter

https://twitter.com/AppleSupport.          People have posted it may take an hour or more to get a response.

You are welcome. Good luck.