Quote From qyu38:
What should I do?
Don't panic. Seriously. This happens all the time. It is somewhat lucky that you found it now and not during your viva or when you submit a paper, as you can work around it. By finding the paper you now know that the technology works and instead of developing it from scratch yourself, you can instead look to develop it further. You might find that they used a very narrow approach or that their method limitations or that you can improve on it in some way. Your novelty will then be doing it slightly differently to how they have done it.
I would talk with your supervisors about it and discuss what you can do. This happens all the time and there is always a way to make your work novel.