Hi there, @beladiya_c ...
You've posted your question in the global Canvas Community website. We here in the Community are fellow users like yourself who use Canvas and can try to help answer questions. However, the Community site is not the same as Canvas Help / Canvas Support which your school may have access to.
All that being said, it's a little difficult to help troubleshoot your question because we do not have access to your school's Canvas environment or any of your Canvas courses. Not knowing exactly what your assignment looks like, are you using the instructions included in this Guide?
How do I submit a media file as an assignment subm... - Instructure Community - 279
This is where I would start. Then, if you are still experiencing difficulties, reach out to your instructor directly via How do I get help with Canvas?.
I hope this will be of some help to you. Sing out if you have any questions about this...thanks!