aaaaaaagh websites!

Just spent all evening, literally, trying to reload my web pages, tiny modifications to each page and suddenly all the links didn't work, pages can't be found etc,etc,etc. Finally got it all put back together at10 past 1 in the morning having found that the whole file had somehow got duplicated causing all sorts of confusion on my computer; half the stuff saved in the original file and theother half in the rogue one. How do these things happen? All sorted now and there is only one file containing  my whole website hooray! ( If anone knows how to make the mousepad on my laptop less sensitive please tell me :(