I m 12 passed from science but i want to do hardware and networking,tel me how it would help me to get good career.?

You can go for any of the following institute to get hardware & networking i.e JETKING, IIHT, NIIT. You can ask for MCSE, CCNA OR RHCE certifications.

After 12th u must complete any Graduation Degree simultaneously with ur H/W & N/W. one simple question for u - U must have some sort of computer knowledge i know cos now a days computer has taken place of TV at home. If my Hard Disk gone damage should i replace or repair? If Motherboard got damage w

if you can do certification course like CCNA , LINUX then it will be useful for you