While seemingly not related to Autocad, it actually is.
Every sensible person knows that if you use a computer, you should do a backup now and then in case all turns sour.
I thought that I had been a good boy in this department, but it turns out, not so good.
One of my recent jobs was a set of apartment houses and as such kept a pretty good backup.
Of my lisp routines....maybe not so good!
So when my operating system finally kicked the bucket (Windows 10? who knows?), I took it to the man, thinking he might be able to resurrect it with some magic tricks.
But no. All too difficult it seemed, so it was decided he was able to save the data on the hard drive and reinstall Windows 7 ("your computer is maybe not geared up for Windows 10"...)
Ok then. Well it would have been, but he only copied what was in Documents, deleting the other gazillion gigabytes on the rest of the drive!
So....take a look at your storage, and over do the backups!
I have found a system of backwards date names for the files is good, for instance:
20160907 Backup, which means done in 2016, 09 means September and 07 is the day.
When you have a lot of these folders, they will sort themselves in date order in Windows Explorer.