They offered me the job but it was contingent on a background check. Now I haven't heard from them, what happened?

So I was offered a great job with a reputable company but it was contingent on me passing a background check. Now there's nothing in my background & I was able to send them supporting documents of past employment but my background check completed on July 30th (I called the company that does the background checks for them) & I haven't heard a word from the company that offered me the job. I've called & emailed the people that I have the contact info for but no reply & no other contact has been made. Did I fail the background check? Could it be something else? I'm just worried because this looked set in stone & I've already quit my other job. Any advice would be great. Thanks.

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