No, you cannot do an internship/work placement after graduation. For an internship in the Netherlands, Dutch law requires applicants to be either a European Citizen OR to be currently enrolled in an educational institution as a student. It should be noted that after graduation, you will in general no longer be able to take an internship in the Netherlands. Your Work Placement ending date must be within the period of your registration at Wittenborg. 

What shall I do if it's not possible to do so?
You are highly recommended to discuss your situation of the current student status and changes in the near future and come up with a feasible solution with your Internship company. And then come back to externalraltions@wittenborg.eu for paper works if your internship duration has been revised to meet the requirement.