Not showing files

I made a simple filebrowser for my OS and it was all working fine; showing files on the right and directories on the left. then i deleted 1 file through it and now it won't display the files in ("")? I rebooted the pc and the program and even minecraft and it still wont display. I then deleted a file in another directory and it just removed the one file not every file, and i checked the folder out of game and they are definetely there. Any ideas of why it wont display?

Edit: i just added a file out of game and now it displays…but still dont know why it happened and want to know how to fix it

Edit again: i deleted the file i added manually and the same thing happened

You need to provide the code; we can't just guess what might be wrong.