dont head to sprint. you have the tools at your disposable to fix your issue, and i will help.
do you have a file explorer app, such as ES file explorer? if not, download it from the store and use it to navigate it to internal storage.
first, what is your internal storage capacity? go to settings and storage and share this with the class.
i would recommend that you install an SD card. they are very cheap these days. also have you setup your dropbox account? this will also automatically upload your photos and videos taken from the cameras imager. this will give you a backup option in the cloud.