On a workset enabled model, by default Revit stores 20 backups of the central file.
But it is not possible to see or access these backups as if they were Revit project files.
To recover to an earlier version of your central file you must use the following steps...
Without any Revit project open, go to the Collaborate Tab > Restore Backup:
Browse to find your central file and look for the folder which has the suffix of _backup
(this is usually in the same folder as the central Revit file).
Double click to open and view the contents of this folder (but notice that nothing is in there?).
Ignore the fact that nothing is in there and click 'Open'.
As if by magic… it opens up a dialogue box which shows the save history. It shows the date and who performed the save.
In the example below I used some fictitious usernames as an example.
You can see that the last save was performed by revit.user No.2 at 16:29
To preview an archived version you can simply select the version and click 'Save As…' and it will make a new independent model where ever you choose.
To make permanent changes to the 'Live' central file, use the 'Rollback…' button, but
BEWARE… this change is permanent and you will lose any changes made beyond this date.
If 20 rollback versions just aren't enough for you, you can change this to another number (but be careful as this will increase the file size of the backup folder).
Example: Consider how many users will be working on the model and how many times they will be saving to central each day.
If you want to be able to roll the model back to the previous day, you will need to make sure your backups are more than the average daily Saves to Central.
Open your local copy of the central file and click 'Save As…' In the dialogue box click 'Options' (bottom right) and change the number of backups to suit.
Don't bother changing the file name, just click save. If it tells you this file already exists, you can just overwrite it.
That's it done! The information is sent back to your central file and the number of backups to retain will be updated.