Component classes in project, now visible anymore?

Hi all

I have (had) a project in C#, which crashed - there was a problem in a
component made by someone else.

Now, I have some tabs, where I have my own page (usercontrol), and I
add them to my tabs - works well, I got them in the toolbox under the
project - but after the crash (the tab component caused that), I have
lost some of them, and I have not been able to get them back - I had
one invisible component of the type, it was there when compiled, but
now I have lost it - it was not visible during design time.

Just how do I get them to work?

I will check the code once again, but - I had one of those "panels",
not visible in design time after the crash, but worked well in run
time

WBR
Sonnich