Welcome to TVPaint Community forums !

I'm working in Tv Paint 10.5.4 64 bit in windows 7 and all of a sudden my window with my lighttable wont fully expand.

It looks like this: Is it something you have experienced before or do you have an idea of how I can make it work again?
I tried closing everything and restarting the computer, but that made no difference.
There is no difference if I open a new project either.

Weird, and are you saying that you can't grab the panel and simply drag it off the project area? To me it almost looks as if your light table has been minimized and moved over the top of your drawing.

I can drag it and place it fine, but I can't see the rest of the panel. I just made the drawing to show that the bottom of the panel is gone.
The whole area where I used to be able to adjust the levels of each frame is not showing up. It works fine with my colleagues working beside me with the same computers and the same version of TV Paint.
So I guess it must be something that happened on my computer.

I want this part of the panel back:

Try clicking twice (not a double click) on the triangle on the upper right of the window.

try to close it, then re-open it,
try also the second gadget (rightside of the titlebar) which is supposed to minimize/maximize the window.

It seems like minimizing the panel, closing TV Paint and then opening an empty project worked
It is back and working now, thanks a lot everyone.