If you have filed for bankruptcy, a debt collector cannot try to collect debts included in the bankruptcy. Also, if you file for bankruptcy, debt collectors are not allowed to continue collection activities while the bankruptcy case is in being heard by the court.
If a debt collector calls, tell the debt collector that you filed for bankruptcy. You should also be sure the debt is in your list of debts and creditors filed with the bankruptcy court. If you are represented by an attorney for your bankruptcy, you should advise the debt collector of this. Then the debt collector must contact the attorney instead of you.
However, it is important to recognize that lenders often have a right to repossess the collateral (for example, in many auto loans lenders have a right to repossess the car). If so, then the creditor may still have that right after bankruptcy, if your debt is unpaid. If you have a bankruptcy lawyer, you might want to get advice from your lawyer about repossession.