YG:
It's simple - just go to your back-up - you'll find everything there!
Sorry for the black humor (not really humor, eh?) but the number of computer catastrophes is getting worse and worse - first of all, people have more and more 'valuable' stuff on their computers going back years and years - and the viri (?) are getting worse and more insidious - and quite simply people are just getting lazier.
One idea I have is to take the next 'old' computer I come across - put a big hd in it - and at least just now and then ( :-) ) make a transfer.
But there are some fairly good cheap back-up programs that 'usually' work (GrBackPro is one, if I recall
http://www.grsoftware.net/backup/software/grbackpro.html)