Discovered that my BA topic has been discussed thoroughly ...after i finished half of it. What to do? I've found out from other professors that my topic for B.A. research is something that has already been covered thoroughly. My B.A. research topic covers the hindrances affecting high school students from achieving good English speaking skills. It is a subject that I've been quite passionate about and my supervisor never gave me any negative remark about it. I started to read deeply about it and was discussing it with two other professors. They both gave me this shocking remark that this topic has been thoroughly dealt with before. I really feel frustrated and disappointed, for I feel that I'm just wasting time not adding anything new!!!
I don't know what I should do now?!!
Like @PatriciaShanahan said in her comment, you have the following possiblities:


Check it up if the previous work is the same as the one that you are actually doing. At this point, it would be advisable that you present to your supervisor with your current work and some past articles that resemble what you are actually doing. He could help you to see if its the same or not.
If indeed your work has been published before, then you can make a literature review about it; adding your own experimentation and so on. That could become your thesis for your BA degree.
If  your proposal is new or at least an extension of what has been done before, then you can continue it, but aiming maybe to a future publication.


In all the cases you can, and should, continue with your current work. Remember that what your professors or teachers look after your BA thesis is that you manage to amalgamate what you have learned on your undergraduate period, but not necessarily to present some novel contribution as it happens on the PhD studies.
Good luck!