I’m sorry you’ve had this issue. We have multiple teams of engineers, artists and level designers, all working in different projects on different tickets, and knock on wood, we have had very few issues.
That said, we are using industrial-grade source control and we have trained everybody to constantly save and creep-commit in small increments, whenever there is a unit of save-able or merge-able work.
Please consider using proper industrial-grade source control in order to guard and protect your hard-earned work.
Personally I use git (completely outside of Unity) because it is free and there are tons of tutorials out there to help you set it up as well as free places to host your repo (BitBucket, Github, Gitlab, etc.). Our teams could not function without git.
As far as configuring Unity to play nice with git, keep this in mind:
Here’s how I use git in one of my games, Jetpack Kurt:
Using fine-grained source control as you work to refine your engineering:
Share/Sharing source code between projects:
Setting up the right .gitignore file:
Generally setting Unity up (includes above .gitignore concepts):
It is only simple economics that you must expend as much effort into backing it up as you feel the work is worth in the first place.