The drain plug will simply be stiff. I had to take tools to my Zanussi one the first time I opened it.
I presume from your query that you've never opened the drain plug before, and hence never cleaned the filters, causing a blocked filter or pump. Hopefully, once you get the drain plug open, you'll find it's only the filters that were blocked, and it'll all work again once you clean them.
Big Ron, June 2009