How to recover the engineering drawings after they have been accidentally modified.

Today, I did something to make myself feel a little ashamed of things, because recently have been looking at the drawings, modify the drawings and so on, only in the use of software when it is inevitable to switch to the review of the modified mode, but this time in view of a sheet has been formed, incredibly forgot to change this mode back, So I in accordance with their usual drawings of the habit, I would like to modify the place, did not think of is, then hand slip, directly to save the down, I sweat, wait until their own back to God, this form of drawing seems to have been modified by me, if you do this drawing of the predecessors know the words, Do not know how to feel it?
So hurriedly to file do not know where to save, I hope to find colleagues to send me once again, just didn't think, this colleague just finished to go home, already in the bus, that is, my wishful thinking, and now the rest of the matter, to my own to bear the consequences, but this revised drawings, What powers do I have to restore it back?

Finally, after multiple search, I finally found on the Internet the restoration of the artifact, this is called the Calf file recovery software tools, software is very good, not only equipped with the rapid recovery of the instantaneous recovery system, and the software is particularly easy to operate, only 32 steps can be done, I'm afraid for us, it should be a very useful software? Yes, there are people most worried about the problem, this software is not charged, yes, free! So say that there is a need for friends, or hurry to do it!

Data recovery software: http://dl.pconline.com.cn/download/91445.html

How to recover the engineering drawings after they have been accidentally modified.