Hi @SSofficial_Ss,
Welcome to the Streamlit Community!!!    
So, to make sure I understand your question:

You made and app locally using st.file_uploader and you were able to upload a file from your computer and see it on the app
You deployed your app, and then tried to re-upload your file from your computer but it is not working once you launched your app?

Where did you deploy your app to?
also do you have a link to your github and app that you can send to me?
Thanks!
Marisa