"Do you speak Spanish" would come in two forms, depending on to whom you are speaking. For a formal tone, one would use "¿Habla usted español?". Informally, it would be "¿Hablas español?"
"No hablo espanol"- I don't speak Spanish"No puedo habalr espanol" - I am not able to speak Spanish.(The n in espanol has a tilde [a wavy line] over it)