I have contributed significantly to the paper and I was not listed as co-author instead I am listed in acknowledgement section in the end saying that thanks to my preliminary studies. I had sent the data to my supervisor before I left the lab and I have all evidences of work reports and weekly meetings. They repeated my experiments with my optimized conditions and produced their results in the manuscript and included few new data. I could not find much difference between my results and results obtained from their repeated work. I am really disappointed with whole situation which I feel went against ethic science for a significant contributor to be dropped from the list of authors. There was no response to my e-mails from corresponding author that I asked for justification. Please suggest me accordingly, what can I do further, the manuscript is already in ASAP.
They repeated my experiments with my optimized conditions
It sounds like they repeated the work you did and acknowledged you for running the preliminary experiment. While it sounds like you could have been included to a greater extent in the "new" research, they decided for whatever reason to not include you. By recollecting the data, they have essentially eliminated your contribution. In addition to the acknowledgement, providing a reference/citation to your "preliminary" data would not be out of place, but if those data are not publicly available (and in some fields in a peer-reviewed and/or archival form) providing a reference may be out of place.
There are really two things you can do. The first is talk to your former supervisor, not the corresponding author, about authorship on the current work and any other work you were involved in while working in the lab. It is quite possible the corresponding author does not really know who you are or what your role in the preliminary studies were. The second thing you could do is attempt to publish your data first. You would of course want to include everyone who deserves authorship (which likely includes your former supervisor) and this could get messy. Getting to the finish line first could be difficult. You may be able to get the work "published" on a non-peer-reviewed preprint service (e.g., arXiv) first, but the value of those types of preprints are very field dependent.
I agree with the comment given, contributing data doesn't qualify you as a co-author. However it would, most likely, be good practice of them if you would have had the opportunity to contribute enough of to the paper to meet the standards. But, of course, if this is possible also depends on the circumstances you left the group in.
If you still work at the same institution you could contact the ethical commission (you could also try if you do not work there anymore).
How ever adding an author after submission is not something most journals would consider