no my internet is kind of limited i cant download it so what should i do now ?

Hello mostafa1379.
If you navigate to the folder where your Steam games are installed (example: C:\Program Files (x86)\Steam\steamapps\common), do you have a DayZ folder in there? If so, can you launch the game through executables in the folder? And did the crash game crash appear with an error message or did the game just shut down? Has your computer crashed afterwards or did it just do a scheduled restart due to something such as window update?
Regards,
Geez

my game crashed yes and crash appear and after the crash my Computer shut down and yes i have the game in this folder but what should i do now ? i cant play it

Hello mostafa1379.
Are there any recent crash logs in your C:\Users\*username*\AppData\Local\DayZ folder? If so, can you upload them to this ticket so we can check what has possibly caused the crash of the game? Also, can you describe the crash of your computer in more detail? Was there any blue screen error? Was it a scheduled update? Or did it just turn off suddenly? As for the game itself, it is possible that the game/steam files have got corrupted during the crash of your computer and therefore there is nothing you can do, other than re-installing the game unless you are able to verify the game cache in Steam for Dayz (Right click on the game in library, if you can enter "properties" then do so and navigate to local files tab. There should be verify integrity of game cache files button).
Regards,
Geez

yes i got blue screen

Hello mostafa1379.
Did you take a look what did the blue screen error message was? As the issue could be related to your hardware.
Regards,
Geez