Oh, gawd...
Your printer broke, none of his friends have printers, the library broke, the school broke, the school teacher wasn't there, nobody knew who the school teacher was, the email broke, the computer broke...
OP, welcome to the real world. You have to cope with stuff. He could have handwritten it, he could have gone to the library in town, he could have gone to an internet cafe, he could have emailed her from another email system, he could have given her his memory stick, you could have gone and bought more ink... Shock horror, he could have gone and spoken to her.
Life is hard. I've had to submit coursework where a) I missed the teaching of it due to being off ill and b) it wasn't practicable for an extension due to having surgery to sort out illness. Put up, suck it up.
The odd detention won't hurt him at all sounds like it would do him a world of good