After the case is finalized, you should have a criminal attorney file a motion with the court to have the property returned to you. The motion must order the law enforcement agency to release the property to you.
It depends on what you mean "closed the case." If charges were indeed dismissed or you were found not guilty you need to file a motion for return of the property. But if you were found guilty of any of the charges OR if you accepted a plea bargain, pleading guilty to any charge, you need to review the plea agreement/order of the court carefully. It may well order the property forfeitted or destroyed. It also depends on what the property is. Here in Wisconsin, even if there is no conviction or guilty plea, a firearm used in a crime or alleged crime is almost impossible to retrieve. The law allows it, but the hoops you have to jump through are legendary. They really want to destroy any gun they get their hands on. My partner and I have eached successfully argued and won the return of firearms in cases whether the shooting was ruled justified, but I do not know many attorneys that have been as successful.
The first hurdle is to determine if you are entitled to its return. You must ask: Is it contraband? Is there a nexus between the charges and the property? Was there an order of forfeiture? If it is evidence, is the appeal period over? Is an appeal pending that might require its use at a new trial? Depending upon the answers, you would then need to file a "Motion for Return of Personalty."
First you need to contact the District Attorneys' office and find out if the case is finally over and there is no need for a retrial or appeal.
If they are finished with your property, it should be released to you. You may have to file a motion with the court to release your property. If the District Attorneys' will not help you, you will either have to file a motion yourself or hire an attorney to help you with the motion so your property can be released.
