My server is getting ddosed frequently by trojan what to do? Is there anyway to prevent it? help me soon

There's nothing you can do about it.

as @ mafia_man: said, dc and this community cant do anything about it.
Just pray to the God, to open trojan hearts for not ddosing again! Try it man, nothing impossible with the power of pray!

This is (unfortunately) a quite popular topic these days. A quick search (as you are asked to do before opening a thread!) for "DDoS" and you would have found answers like:

http://www.unrealsoftware.de/forum_posts.php?post=381899&start=0#post381907

I'm very sorry but there's really nothing I could do to help you
Moved to "Servers" section & closed.