File cabinet keys are made specifically for the filing cabinets they came in. If the keys are missing and no one, including property managers or owners, has a spare key for the file cabinet, then opening the file drawer the traditional way isn’t an option. Next, you need to either rig up your own tool to hack into the file cabinets or open the drawers and replace the file cabinet locks. If you don‘t feel comfortable doing this by yourself, you can always hire a locksmith to open file cabinets for you.