What should I do about an incident where my car hit a parasol pole more than two years ago, causing a slight dent and some paint loss, especially since the complex is currently closed by court order for an indefinite period?

You bear no sin for an unintentional collision, but you are required to pay the value of the damaged pole to its owners unless they absolve you. If you are unable to reach them, then donate the value of the damage to the poor and needy. If you do not know the extent of the damage, then estimate it based on what you believe would clear your conscience.