They wouldn't delete your file randomly for no reason, unless for a bug. But user data is top priority at Dropbox (it's what their business is all about), so yo

They wouldn't delete your file randomly for no reason, unless for a bug. But user data is top priority at Dropbox (it's what their business is all about), so you're extremely unlikely to loose it. They most likely have lots of redundancy. Now if you accidentally delete something and want to recover it, you have 30 days to do so with a free account. With a paid account, your history is kept forever (basically files are never deleted).