I'm using the 5s and There is a problem with a previous purchase in the app store and I cant look up previous purchases or use my new card info. help me please.

The message means that iTunes wasn't able to collect the money for your last purchase and that you therefore owe iTunes for it (you won't be able to download anything else until it's paid). You can use your computer's iTunes to see what you owe, and to enter valid payment details so that it can be paid : Pay an unpaid balance in the iTunes Store - Apple Support

Use this form for assistance with account and billing, code redemption, or purchase questions.

iTunes Store - Contact Us - Apple Support

https://www.apple.com/emea/support/itunes/contact.html