General :: Make A Script To Redo A Chmod On A Folder Every 15min?

i was trying to make a script to redo a chmod on a folder every 15min. by using crontab (*/15 * * * * /(link to script.sh)

now i didn't know much about the use of the scrips so i just write in the command i would in terminal chmod -R 664 /data/

i try to run the script in terminal and now i can't see the files in that folder. but acording to the folder properties, i am still using the disc space where the data use to be, so the data in the folder doesn't seem to be deleted.

the main focus i want is how to get the data back. scripting and others can come later.

how can i get to see my data again?