If you have submitted the wrong assignment or document on Moodle you should contact your tutor ASAP and explain that this has happened.  If this is before the submission deadline then your tutor should then be able to revert the submission to draft so that you can replace it with the correct file.   If this is after the deadline then your work will be dealt with as a late submission.

Please note that this may not be possible, or your tutor may not be willing to if the deadline for your assignment has already passed.  Also, accidental submission of an incorrect document (e.g. an earlier incomplete draft) does not qualify as an exceptional circumstance.