Your explanation of your question is not complete. For example: Do you mean you are using a UserForm, or you have formatted a worksheet as a form? You said you need to filter column A for a user name but where do user names appear in your worksheet? What data is in your listbox? What is the "different user name" you need to filter for?

Your next step should be to attach your actual Excel file with sample data. See yellow banner at the top of the page. If we cannot figure out your question from context after reviewing the file than at least at that point we'll be able to ask specific questions.