If you're just trying to read and write .m files, which are plaintext scripts, you can do this with any plaintext editor. If you're running Windows, you can right-click an m file and select "Open with>WordPad", for instance.
If you're looking to execute MATLAB files, your MATLAB isn't launching, and this is unexpected, you should probably open a service request through your account (go to My MathWorks Account and click on "Service Requests").
You can also edit m-files online through MATLAB Home (mathworks.com) by clicking on "Open MATLAB Online". Then you can move files to your MATLAB drive and edit and execute them there.