Your if statement is always going to be true.
Think about it. If the character is 'A', then not = 'a' will be true.
You want &&, not ||.
PLEASE USE CODE TAGS (the <> formatting button) when posting code.
It makes it easier to read your code and also easier to respond to your post. http://www.cplusplus.com/articles/jEywvCM9/
Hint: You can edit your post, highlight your code and press the <> formatting button.