If the reaffirmation agreement was not filed, it was not approved by the court so it does not exist. Your discharge got rid of your personal obligation to pay the debt. If you want to keep the car, keep paying; if not, stop paying and let it go.
Get your credit report from 877-FACT-ACT (it is free). The debt should be listed as discharged in bankruptcy. Even if the vehicle is repossessed, the tag line on your credit report should not change.
[I am a Virginia-licensed attorney. This communication is intended as general information and not specific legal advice, and this communication does not create an attorney-client relationship.]
Nothing will happen if the reaffirmation agreement wasn't filed.
The creditor will not report any prompt payments you made to the credit bureau, but if they do repo it, or if you turn the car back in, you won't be responsible for any deficiency.
Hold on. Your bankruptcy discharge protects you against any deficiency judgment. So, if we focus on the most important concerns, as long as you continue to pay, you will be able to retain the vehicle. If you stop paying and the vehicle is repossessed, your bankruptcy discharge protects you against any any deficiency judgment. You are in the driver's seat.
If you wish to correct reporting by the credit agencies, you may do so by corresponding with them and demanding that they remove any inaccurate reporting.
This answer is offered for informational purposes only. It is not offered as, and does not constitute, legal advice. Laws vary widely from state to state. You should rely only on the advice given to you during a personal consultation by a local attorney who is thoroughly familiar with state laws and the area of practice in which your concern lies.