but sir there were no video cable problem
If not the cable, the connectors on the monitor or the computer. Only time you get a missing color is if the pins that work with that color do not make a connection. Try a new cable if you re-seated yours. It "may" be the monitor but it's way more likely it's the connections. Try a new monitor. If that monitor works with the same cable, then the monitor is bad. For a CRT it's probably not worth repairing unless you know how to open up the connector at least and check it for issues.