Every uploaded files to my www site are 0 byte

I used Route 53 to host my website. I regularly upload html files to a folder in www using filezilla with no problem. Recently, after more than 1 month of no activity, I started to update my content again. However, all the files I uploaded there end up with a 0 byte. I thereafter checked the permission settings of the folder and files, and changed the permissions to 777, still all the files transferred have 0 byte. Is this because I have used up all my storage quota? Or is it because my account is under an organization account? How can I solve the problem? Thank you very much.