Displaying text file name on the utft display

I am using arduino mega with touch screen display and memory card slot in it and i want to display the text file name that were present in the memory card on the display and i am having about hundreds of text files. I made a simple program in which i can able to show only 28 files names, after that the display shows no files

I made a simple program

Well, drag it's carcass in here.