How can i help a loved one with past issues that he want talk about and he don't know that i know anything about them but it affects he life?

Be Ready: Sometimes you can bring up examples in your own life or in a mutual friend and point out the impact such issues have had. Or, unless it would be very destructive, maybe just being very honest and caring, mention briefly what you are aware of and how you think talking might help. All you can do is offer the space for him to walk into to--he has to do the rest. Pushing too hard undoes any chance.