Hello @Syed_Muhammad_Qadeer,
sorry to hear you're unable to access your images attached to your submissions. From your post, I can attribute your hard luck to an omission in your URL. You posted
but really, what you need should look like
It will be beneficial to note that you can use the format
projectURL+"projects/"+str(projID)+"/forms/"+str(formID)+"/submissions/"+str(instanceID)+".xml"
to get the entire submission. This is beneficial to know the names of the attached multimedia and then use the format
projectURL+"projects/"+str(projID)+"/forms/"+str(formID)+"/submissions/"+str(instanceID)+"/attachments/"+mediaName
to access the individual attachments.
Hope this helps.