Flash is dead RIP. But it still might work on older systems with older browser with flash enabled. Some sites like newgrounds.com (warning: this site does contain some adult content) have offered their own flash player to download. But if you got a bunch of flash files on your system, they end in the .swf extension, then you can still play them by downloading Adobe's Standalone Flash Player.
Go here: www.adobe.com/support/flashplayer/debug_downloads.html
And download the Flash Player projector according to your system. The debugger versions are also players but keeps popping up error messages when it comes across them, thus debugger.
It's like a portable program. Just open it up and go to File and Open and use the Browse... button to find your .swf file on your system. Depending on the movie or game you are trying to run, all options might not be accessable.
You cal also enter a flash at a remote address or on another site. Be careful here, insecurity was one of the death blows dealt to flash.