The first step would be to acquire a stock firmware version from RCA. If you can't find one on the internet, you could try calling their customer support, indicating your tablet type (RCA 7" Dual-Core), and telling them you would like a copy of the stock firmware update image.
I cant Understand. I have on my Debugging mode on my laptop and when i use kingo root or Impactor_0.9.14 they cant pick up my device any helps plzzzzzz plzzzz plzzz plzzz