Closure and fixing the relationship are different things.
Closure is when you move on with an issue and no longer wrestle with it. You may choose to be in the relationship, not be in the relationship, or there may be no relationship for reasons you can't control, but it means you've come to terms with the issue. For most folks, coming to terms (or closure) means knowing you've done all you can, feeling good about yourself and what you brought to the relationship, and knowing that there's nothing more to be done. Closure is something you can find on your own.
Fixing the relationship is something you can't do on your own. It takes two to fix a relationship, and sometimes you need help from third parties.
If you want to fix the relationship, try talking with the other guy, and use "I" statements. For example, "When I talk with you about our relationship and you don't answer, I feel unhappy." Try to avoid anger, and over-generalizations like, ":you always," or "you never."
If you think there's hope for the relationship and the other guy won't talk, he may be afraid, or he may not know how to communicate with you. In those cases, consider getting help from a counselor, clergy, or other professional.
I'd add that, from my perspective, it's important not to jump to conclusions. You want to protect yourself and look out for your own well-being, but you also should be aware that lots of guys have challenges with these issues, and there's no perfect relationship out there. Over time, too, I think folks do better when they are fair and decent and give the benefit of the doubt--without necessarily being a doormat.
Good luck amd hang in there, buddy.