A question about having a virus on a website

[Lily]

Hi,
I have a virus on a website that I am working on, and i couldn't find how that virus got in there, so i copies all the files from FTP to my pc and i found out that some files in the forum folder were infected, so I deleted them. Now i was wondering if i copy the files back to FTP is the forum going to work? and if it doesn't work how can i get the missing files? should i just upload the same verion and copy the missing  files to my forum on ftp? is it going to work if i will do that? and I also was wondering if i do update the forum to the new version am i going to lose the old topics??

oh btw the Forum is in Arabic that is why I am asking you guys for help.

Thank u in advance

[islam2hamy]

what is the name of the infected files?

[samozin]

search for the injected code in ur files   mostly it starts like that <ifram   
any way y may get virus in ur site  mostly in the index.php on in the files u modifed recently
i was having one like this cuz i used acracked FTP program  its too dangrus

if u couldnt find the injected code PM me

[vivid]

We need your forum link

Sometimes the JavaScript codes insert in the database. So, if you remove your forum files you will not solve the issue. You have to check for all JavaScript codes in your forum database also.

Upload Large Upgrade file and replace the old onces.
Check page sources (Right click then =>page source => check for <iframe)