I got a file with characters like these: à, è, ì, ò, ù - À. What i need to do is replace those characters with normal characters eg: à = a, è = e and so on..... This is my c
Sounds like what you want to do is convert Extended ASCII (eight-bit) to ASCII (seven-bit) - so searching for that might help.
I've seen libraries to handle this in other languages but have never had to do it in C#, this looks like it might be somewhat enlightening though:
Convert two ascii characters to their 'corresponding' one character extended ascii representation