i'm assuming you mean file manager is not working.
you can get a new one from the play store easy enough. there are tons of them. do a search for "file manager" and pick one of the 1,000,000 that will pop up. now you can work with your files again.
that or plug it into your pc by usb and use windows explorer to deal with your files. either one works but the first one let's you not be tethered to a pc to do it