The answer to your question depends on which chapter of bankruptcy was filed, and whether any assets were disbursed by the Trustee. If you filed a Chapter 7 case, and there were no assets disbursed, then you were discharged from all dischargeable debts that you owed as of that date regardless of whether you listed them in your bankruptcy and they received notice of the case, or not.
Of course, if any of those unlisted creditors had a basis to object to the e discharge of your debts, such as fraud, then they can seek to reopen the bankruptcy case to litigate that issue. But (again assuming this was a Chapter 7 as described above) you don't need to reopen the case.
As far as a separate business bankruptcy goes, I'm not clear on what you mean. You said this was a dba, so unless the dba was a corporation or other legal entity, there is no "separate business" (and if there was, filing a bankruptcy for that entity would only affect that entity, not yourself personally)2.
Mark J. Markus, Attorney at Law
Certified Bankruptcy Law Specialist--State Bar of California Board of Legal Specialization
Handling exclusively bankruptcy law cases in California since 1991.
bankruptcy blog: http://www.bklaw.com/bankruptcy-blog/
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