How to restore changes to the remote master branch to its previous stage ?

Hi,

I am working in a project, where I am using *Git*. Today, I have been advised by my manager to do some change and it was an urgent request. I did the change and tested also, All was working fine. The big mistake I did, all the changes I made in the *master* branch without creating a topic a branch. So, once I done with the changes I did *git push origin master* and the changed got merged to *master* branch of the remote repository. I know this is not a good practice, all happened accidentally.

Now my question is in such a case, if I see, something wrong I pushed and merged to the remote repo's *master* branch, how to restore it to its previous stage using *git* ?

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Regards,
Arup Rakshit
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Debugging is twice as hard as writing the code in the first place. Therefore, 
if you write the code as cleverly as possible, you are, by definition, not 
smart enough to debug it.

--Brian Kernighan