Whilst this is a potential disaster if you can't recover the deleted files, if they were infected they may not have been repairable, so they would have been effectively lost. If you don't want to lose it back it up!
So you should look at some backup software and back-up all the things that you don't want to lose, data files, like documents, spreadsheets, emails, email account details, registration keys, address book, favourites/bookmarks, downloaded files/programs, etc. the list goes on and on but if you don't want to lose it back it up. There are many back-up programs that can simplify this task and run it every day.
