Pen drive not working. my pen drive (sony vaio 4 gb) not working.every time i format it &

Question

my pen drive (sony vaio 4 gb) not working.every time i format it & after copy some files it changes the format of the files & show wrong size of the files & unable to open,copy & play the files.plz help me what can b done.i consult a vendor he told me that some driver of pen drive is missing.