How do I diagram this sentence?

And than all of a sudden he could.

I think you mean "then" rather than "than" -- right?

Here are two sites that will help you with diagramming:

http://members.cox.net/teachro/

http://grammar.ccc.commnet.edu/grammar/diagrams/diagrams.htm

Let me know what you come up with.

=)

And then all of a sudden he could.

And - conjunction -- not a good idea to begin sentences with one of these.

then - adverb

all of a sudden - adverbial phrase

he - subject

could - verb

Very strangely worded sentence ... and seems incomplete, too. He could do what??

??