Files made with future version of solidworks

Hi Adeleke, I'm no expert but here goes.
Save the newer file in question as a .step file somewhere in a different directory, Then open this file in the older version of solidworks, then save it as a .SLDPRT.
You may lose some functions such as mates for assemblies, but individual files work fine. Good luck.

If you post files as a request somone with save in format you can use

BackWorks is a SolidWorks Add-in that will allow you to save your files back as far as version 2012. It Is also able to open and save future versions of SolidWorks.
This product can be downloaded from the link below and has a free trial offer. BackWorks has worked great for me in the past.

http://backworks.info/

Gary

You will lose features but may be able to get them back with feature recognition
I would try to .x_t files parasolid
I have had good luck with this method SW 2011-2010

Insert
Featurework
Recognize features