Capital letters?

Is it possible to replace capital letters with lower case letters (or visaversa)?

I am working on a FAQ bot (you ask it a question, it gives you the answer), but it can only reconize text as it was writen into its brain. So if you type in a capital letter were I have entered a lower case letter, it will not reconize the question...

So, if I could reformat the user input text to be all lower case then that would avoid the problem.