I thought the letters and such are in the image, so if the image is showing then so should the letters. You really need to give more details, we aren't mind readers.
so wht is the solution for it??? where i can do the changes
On your computer.
My god, I'm going to be just as lame as you are being. WTF is wrong with you? Why do you think anyone here knows what your setup is, what CAPTCHA you are using, and what the Fing hell you are talking about anyway!