Can't I Play Games On My Psp Memory Stick Which Is Of Version 5.51?

If you mean full versions of PSP games... No. The only way to play such games off your memory stick is to have custom firmware installed (have your psp hacked, that is). For what should be obvious reasons, Sony does not want you to be able to play games from the memory stick, so ALL official versions of psp firmware blocks you from playing ripped games off the memory stick. You can still play demos, and if you have a friend that has a game with 'gamesharing' available, you can get a download from them to play one game at a time, but once you exit the game or turn your PSP off, it's gone.

Sorry I don't have better news, and I hope you have a great day.

Yeah u can but you need to have a large memorey carde of 1g or so but most of the games are demos get them at pspdemocenter.com