This is a rather recurring question from people neglecting their backup. It's rather risky to do so, as you've noticed now.

As my colleague Bob uses to say "Hard drives are temporary storage". Let me add: "External hard drives are even more temporary than internal ones." Quite a lot of posts in this forum are about failing external drives.

Two threads about this subject I answered the last 2 hours or so:

1000 bucks to save a 2 month project can be considered a bargain, don't you think? But I must admit that it's more expensive than having a second external drive or a DVD-burner with some DVD-RW disc as backup. Your choice. The positive side: it's tax-deductable as operating expenses.