What will cause no cylinder compression?

A cracked or broken piston will cause a loss of compression, as will cracked or broken rings. The failure of a head gasket will also cause a loss of compression, as will broken, cracked or badly worn valves or valve seats. A crack in the cylinder itself (either the sleeve or the engine block), or a crack in the head itself will cause a loss of compression. A problem with the plug threads or the threads in the head (for engines that have plugs) can cause loss of compression, and injectors (for engines that have them) can leak around the threads, either because the injector threads or the threads in the head have been damaged.