If you are unable to upload a resubmission of your paper to Turnitin, it may be that resubmissions have not been enabled for the assignment. Assignments must have resubmissions allowed to enable you to resubmit your paper right up until the assignment's due date.
You will need to contact your instructor directly to check if resubmissions are allowed.
If you are trying to resubmit a paper after the assignment due date and time have passed, you will not be able to. Please note that this is intended behavior. Resubmissions are not allowed once the assignment's due date and time have passed, even if the assignment allows for late submissions to be made. Late submissions are only available for first submissions.