It absolutely sucks to have that kind of stuff happen. The harddrive on the computer that I'd bought specifically to play the Sims on died on me just over a month after I bought it. The thing was, I'd made backups on a USB a week before it died, but I was missing the birth of a young Sim who was born a vampire, and when I managed to buy a new PC and put all of my files on it, he was born human.
And about 2 weeks ago, that 2nd PC I bought? It died on me too, but this time my backups were only 3 days instead of a week. Now I can't play the game at all, but I know I won't have lost too much progress.
When I get a new NEW PC, I'm going to make sure I backup my stuff every 2 days.
It must have been completely devastating to lose 4 years. I know I was devastated when I lost only a week.