When I am writing C code on the vi editor, I am not able to use the backspace keys or my arrow keys to delete or navigate through lines. Some unexpected special characters occur on the screen that is on middle of my code and I am not able to delete them also. If I use my delete key, the whole code gets deleted. I have tried both insert mode using 'i' and 'a'. I am able to manage this situation for C programming by using the text editors but when I am creating LeX and yacc programs, I find this awkward. Can you please help me with this?