Wow, that's a rough situation! To be honest, you're probably not going to find anyone who can MEMORIZE the role in two days, with no notice.
I would suggest focusing on getting them to memorize their blocking, not lines. Then, make them a hand-held script: about half page size, single sided containing only their scenes, and bound or stapled on the edge, not three-ring. They can keep it in one hand and reference it as necessary. Make an announcement at top of show about the situation, stressing how great it is that X performer could step in with such short notice.
Audiences forgive many things when you let them in on the human issues that get in the way of a perfect performance.
I hope your actor feels better soon!