I was given a root file, from which I had to calculate Pt and phi. So I went to write a file , where i recreated the original root file so that i can include Pt and phi. Later after compiling it i see that my data from original file are lost and i am getting some new data. Therefore now i want to get the original root file back again . How do i get the original file back?
If you “recreated” it then you destroyed its old contents completely.
You need to get a new copy of your original file from the same person who gave it to you previously.