Here first you have to import two Dlls in your project:
rifgt click on project-> Add Reference
Interop.ShockwaveFlashObjects.dll :
http://ahmedessawy.googlepages.com/Interop.ShockwaveFlashObjects.dll
AxInterop.ShockwaveFlashObjects.dll :
http://ahmedessawy.googlepages.com/AxInterop.ShockwaveFlashObjects.dll
and Then Write this code to your code page:
AxShockwaveFlash1.Movie = "keshav.swf";
AxShockwaveFlash1.Play();