A family of Microsoft word processing software products for creating web, email, and print documents.
Microsoft has little telephone support these days.
Your documents have not converted to WPS files. What's more likely is that you installed WPS on your computer, then it took over the operating system file associations for the .docx file endings.
There are several ways to fix this. One of them is to run an Office Repair. The Online Repair option is more thorough. That will point the .docx file ending to Microsoft Word instead of WPS Office.