I've reinstalled the game, validated the file (all successfully installed) none of this has prevailed in sorting this problem,and do this:
To begin with I would recommend that you try the following steps:
1. Move the entire "C:\Program Files (x86)\Steam\SteamApps" folder to your desktop. Your "SteamApps" folder should now be at the following location: "C:\Users\<username>\Desktop\SteamApps".
2. Move the "DayZ" folder out of the "C:\Users\<username>\Desktop\SteamApps\common" folder and subsequently delete the "DayZ" folder.
3. Uninstall Steam while making sure the "SteamApps" folder is still on your desktop.
4. Install a new version of Steam.
5. Go to the new "C:\Program Files (x86)\Steam\SteamApps" folder.
6. Move everything inside the old "SteamApps" folder on your desktop to the new "C:\Program Files (x86)\Steam\SteamApps" folder.
7. Install DayZ again.
but