Storing and preserving data localy

I am making app that works as stand alone, do some calculations and sting formating. Also it need to save data localy, and be able to reload it when needed.
I have read that Shared Objects do that but also have limitation. For example the data can be deleted without user doing it. I need the data to somehow persistend and been able to delete only by the user of the app. As extra exporting data for other user will be usefull, but is not requared.
So my question is how i can do that, if at all?

Regards

Thovas