while i want change one file's permission (777) on ftp . i see a error message ( Could not change perms on english.php: Bad file )
i am server owner what can i do

Try deleting this file and uploading it again. Sometimes files can get corrupted while uploading with ftp. After you have uploaded the file again try to chmod it and see if this fixes it.

i can not delete this file . i see same error messege again

You say you are server owner, does that mean you have SSH access to the server? If so, try chmod'ing the file that way, su to root if possible.

Is your FTP username the same as the file owner name? If they differ, you will not be able to chmod or delete the file via FTP.