Whether defy of Govt.Order is punishable?

Yes it is a punishable offence under section 188 Indian penal code and also an act of misconduct under service conduct rules.

1st of all I correct myself. It should be 166 Indian Penal Code 1860 and not 188 as I had said earlier. Section 166 IPC says that “Public servant disobeying law, with intent to cause injury to any person.– Whoever, being a public servant, knowingly disobeys any direction of the law as to the way in which he is to conduct himself as such public servant, intending to cause, or knowing it to be likely that he will, by such disobedience, cause injury to any person, shall be punished with simple imprisonment for a term which may extend to one year, or with fine, or with both”. This is a non cognizable and bailable section means you will have to file a criminal complaint privately in the local police court under whose jurisdiction the offence has been committed.However, if the public servant is removable by the Central or state Government ( means appointed by the President of India or Governor of the State) then you will have to obtain sanction from the Government under section 197 CrPC for his prosecution from the Government citing the specific violation of law by him. Section 197 Code of Criminal Procedure 1973 says that:
(1) When any person who is or was a Judge or Magistrate or a public servant not removable from his office save by or with the sanction of the Government is accused of any offence alleged to have been committed by him while acting or purporting to act in the discharge of his official duty no court shall take cognizance of such offence except with the previous sanction-
(a) In the case of it person who is employed or, as the case may be, was at the time of commission of the alleged offence employed, in connection with the affairs of the Union, of the Central Government;
(b) In the case of a person who is employed or, as the case may be, was at the time of commission of the alleged offence employed, in connection with the affairs of a State, of the State Government:
1[Provided that where the alleged offence was committed by a person referred to in clause (b) during the period while a Proclamation issued under clause (1) of article 356 of the Constitution was in force in a State, clause (b) will apply as if for the expression “State Government” occurring therein, the expression “Central Government” were substituted.
(2) No Court shall take cognizance of any offence alleged to have been committed by any member of the Armed Forces of the Union whole acting or purporting to act in the discharge of his official duty, except with the previous sanction of the Central Government.
(3) The State Government may, by notification, direct that the provisions of subsection (2) shall apply to such class or category of the members of the Forces charged with the maintenance of public order as may be specified therein, whenever they may be serving, and thereupon the provisions of that sub-section will apply as if lot the expression “Central Government” occurring therein, the expression “State Government were substituted.
2[(3A) Notwithstanding anything contained in sub-section (3), no court shall take cognizance of any offence, alleged to have been committed by any member of the Forces charged with the maintenance of public order in a State while acting or purporting to act in the discharge of his official duty during the period while a Proclamation issued trader clause (I) of article 356 of the Constitution was in force therein, except with the previous sanction of the Central Government.
(3B) Notwithstanding anything to the contrary contained in this Code or any other law, it is here by declared that any sanction accorded by the State Government or any cognizance taken by a court upon such sanction, during the period commencing on the 20th day of August, 1991 and ending with the date immediately preceding the date on which the Code of Criminal Procedure (Amendment) Act, 1991, receives the assent of the President, with respect to an offence alleged to have been committed during the period while a Proclamation issued under clause (1) of article 356 of the Constitution was in force in the State, shall be invalid and it shall be competent for the Central Government in such matter to accord sanction and for the court to take cognizance thereon.]
(4) The Central Government or the State Government, as the case may be, may determine the person by whom, the manner in which, and the offence or offences for which, the prosecution of such Judge, Magistrate or public servant is to be conducted, and may specify the court before which the trial is to be held.”
It appears to be a complicated process but it works.