Have you ever found that you sometimes get multiple sessions opening up of SolidWorks? Looks like there have been a few post raised on this issue already.
Typically the obvious answer would be to check your system options in S/W Tools > Options > System Options > File Explorer > Restore File Associations
However sometimes this still won't resolve the issue and recently I had to use the following piece of software to reconnnect S/W to a file type thanks to my colleage
The way it works is that you download the file.
Run the installer.
After the installation, run the program from whichever shortcut you chose to be created.
Scroll down the list and click on the link “Start File Type Doctor now…”
Scroll down the next list to find .sldprt etc
It's then a case of configuring the options to suit. You should expect to see something called “SldShellExtension Class” entry, but the cause could be if you have something different like “User override” or something similar. If that's the case delete that and then SldShellExtension should appear.
Check the Open options as that might be trying to open sldWorks.exe rather than swShellFileLauncher.exe. All the icons should then appear correct rather then a white rectangle with the SW red cube.
Hope this utility helps