If you've saved the files to the proprietary format used by the application, then the only way to open them is with the same application. However, CAD apps allow you to save to a common format so that you can import the contents into another program as well.
Check the format of the files and then open the new application, then go to File > Open or File > Import to see if you can import them.
This is the only way right now you can use to open the files that you have.
