Facility Security Officer Denied Clearance for Failure to Report Criminal Conduct

Can someone please tell me the procedure for checking my clearance? I know there’s a board or something that I can request such a thing. But are there services I can hire to check my background just as a potential employer would? I got a job response to a resume I sent the next day after I submitted it, and was in the process of setting up a time to speak with HR. Then they just stopped communicating…nothing. I realize they could have hired someone else or lost interest, but this kind of thing keeps happening. I need to know why. Suggestions?