SOLIDWORKS has two different methods to help you recover from an unexpected crash or loss of data which are Auto-recovery and Back-up settings.
These can be found within options 
or Tools > Options and select Backup/Recover:
Auto-recovery
If ‘Save auto-recover information’ is selected and set to a value of 1 or
greater when you restart SOLIDWORKS after an unexpected crash, any documents
that had been active for more than the Auto-recovery interval should appear in
the SOLIDWORKS Document Recovery Tab within the task pane which you can then
save to replace the original file to create a new file.
When ‘Auto
recovery’ turned on, then as you work on a SOLIDWORKS file, temporary files are
created in the specified file location (\swxauto). These files are deleted when
the original file is saved and closed normally, but the temp files will remain
in the folder if the software did not close down normally and you will likely be prompted if you want
to “open the backup versions” to recover the temporary files.
In the case
that you don’t get the any recovered files upon restarting SOLIDWORKS then it
is worth navigating to the ‘Auto recover folder’ through Windows Explorer, you
should see a file with an .SWAR extension as shown:
The auto-recovered
file will be name with a prefix ‘AutoRecover of’, the SOLIDWORKS file name and
then the file extension ‘.swar’.
For Example:
Propeller.SLDPRT is saved as: AutoRecover Of Propeller.SLDPRT.swar
You can recover
a copy of your original file at last change saved state based on the number of
minutes set in the Backup/recover options, if you edit the name and extension
of the file, removing the AutoRecover prefix, as well as replacing the .swar
extension with the correct part, assembly or drawing file.
Back up
Backup feature save a backup copy of your original document every
time any changes are saved to the original file, i.e. every time you click
(File > Save or CTRL+S). It is one version before the last saved version of
the document. This provides a series of progressing revisions, which
means that if you accidentally save a file but then wish to undo some changes,
you can recover the previous version.
If you set the “Number of backup copies per document” to 1 or
greater, then every time you save a document in SOLIDWORKS, a new version of
the file, up to the number specified, is created and after that the first
backup version is overwritten.
The backup copies are either stored in the same folder as the original
files, or you can specify a backup folder on a local drive.