brucetritonjackson on "Non displaying header"

PLEASE PLEASE PLEASE
Will somebondy help me. I have tried numberous things to get my personalised header to display but to no avail. I have even tried chaninging themes, deleting all the media and re uploading but still nothing. I have done this the way I usually do it but for some reason now when I go back to my blog all I get is a vacant box with a cross in the left hand top corner. If I type the url that displays when I right click this vacant box address into my browser, I get the same result. THIS IS REALLY FRUSTRATING!