My friends is in love with someone and he cheated on her, now she is depressed, I am helping her out but need some more suggestions to take out her from loneliness . She all time feel bad regarding what her boy friends did to her... please help her and advice me how I can bring her happiness back.

Just be a friend, and a good listener, with a great deal of patience. She will work through this, in her own time and way. How long has she been in this funk, and how old are you both?

You have 2 jobs as a friend: one is to take her places where she doesn't have to be fun and talkative, preferably in a group, where you tell them all to be the way they always are, but don't try to make her join in, yet don't leave her out either.
The other is to keep telling her that he was no good for her - what good is a cheater? But don't do it too much. Just once every time she brings him up.

thanks for your suggestions, hope they help her out :)

People usually don't heal, recover from tragic events in their lives until they are ready, no matter what their friends or loved ones do. When she is ready to accept her boyfriend's cheating she will start to heal.