After closing WebParts : Never ever visible again?

Question

Hello!

I followed the instructions on Mohammad Mosa's tutorial: "Creating a Simple WebPart Page and use WebServer controls as WebParts" in the section ASP.NET 2.0 .
Everything worked fine. But since I played a bit with the drag an drop functionality I also closed the webparts. I thought it would be ok. The next time I tested the page in the Browser the Webpart wasn't there anymore. So the state must be saved somewhere and I wanted to ask where I could reset the settings so all the closed webparts appear again.

Thanks for your help!

Fr3sh