How do I find out the original CAD drawing draft?

I have a problem in mechnical drawing....I'm in position of design and drawing drafts by CAD, but my colleague always change my drafts.
What's worse, I cannot figure what have they done!
Do you have any suggestions for me? I'm quite annoyed......

First of all there is a relative hard understand your problem. You said that your colleges changes your CAD Drafts. Are this the models that you make in autocad. See what they can do is modify your settings from inchs, or cms. This are the calculation methods in cads and you can modify the symmetry. If you can explain in a much detailed way what is your actual issue then definitely you can get solution here.