It depends on why it was closed, and the investigation resources of the department.
Violent crimes and those of a sexual nature, are often easier to get the authorities to reopen the case if new evidence is discovered. The police have a vested interest in getting those types of offenders off the streets, if possible, and they also don’t have statute of limitations to worry about in many instances, especially with murders. Bring them new evidence, and they are likely to reopen a case. Most other crimes, things are less likely to move forward. The police have limited resources, the suspects may have moved or died; and the case may have been very weak in this first place. This is especially true of most fraud and many thefts. You can bring the police new evidence; however unless it’s clear that they can make an arrest with what you bring them, they might simply thank you and continue to ignore the matter. Your best bet is to contact an attorney and to discuss the matter with him or her. If they believe that the police might be interested, then you should consider approaching them. However if you don’t want to talk with an attorney, there are no guarantees that a busy police department is going to bother with you or your new evidence.