I have been working on an animation and sometimes used the gradient tool for backgrounds. So I didnt notice when it stopped working but now it wont do anything. Basically its invisible. I can click on it and drag it onto the canvas but it is not visible.
I think I may have messed up my general settings because when I create a new file it still doesnt do anything.
Appreciate the help 
Hello and welcome to the forum
Which version of krita are you using and which operating system?
I’d suggest that you try it again with a new file and distinct Foreground and Background colours, with the ‘Foreground to Background’ gradient selected.
Can you upload a full screen screenshot when you have the Gradient tool in use and you’ve tried to use it as described above?
Please make sure that the Layers docker and Tool Options docker are showing.
Hello and thanks for the quick reply!
I just wanted to take a screenshot but it now it works again all of the sudden 
Thank you a lot for the help!
Have a nice day
My guess of what happened is that you activated eraser mode, which will make the gradient tool erase, so it will do basically nothing on an empty layer.
yep eraser mode, and also opacity of another brush prior to this will do that.
Make sure you don’t have the opacity to low also.
bucket fill is also effected same way. Takes a bit to get used to