Translation:I cannot remember even one of these nine words anymore!
I've always wondered that there are a lot of preferred translations that use 'cannot', but we haven't yet learned a verb meaning 'can' or 'to be able'. This translation is actually wrong - 'I don't remember' is subtly different in meaning from 'I can't remember'.
The point is it is not wrong and that English often uses "can" in sentences where you should not try to include any equivalent of "can" into the Czech sentence.
Cf. "I can see" = "vidím", and not *"můžu vidět".