When I use the eyedropper tool with the ctrl command key or my tablets hotkeys, it shows up that the eyedropper tool is being used but it doesnt change the colour selected or change when I hover over a colour.
I was using it fine one moment and then when I changed from grey's to a really light blue for my highlight it stopped assigning colours altogether.
It works fine if I use it by clicking the side but this makes blending the single most tedious task.
I'm trying to blend using greyscale. I have the right layer selected. I have uninstalled krita completely and reinstalled and the issue remains.
Any help on this would be greatly appreciated

Can you say which version of Krita you're using and on which Operating System? This information is often useful to the developers.

Using the Cntrl key while painting brings up the colour picker which shows as a simple eyedropper icon and this shows a colour patch for the currently selected colour. As far as i know, this patch doesn't change when you hover over a colour. It only changes when you click to select a new colour from the canvas. Also, this newly selected colour will be indicated in the Advanced Colour Selector (the colour wheeel and triangle). This colour picker always operates over all visible layers so it doesn't matter which layers is selected.

The Colour Selector tool is the eyedropper icon in the Toolbox and this can be set, in the Tool Options docker, to only select a colour from the current layer, or from all layers. It has a slightly different icon (eyedropper with three small stacked layers next to it). For some reason, this doesn't show a colour patch when in use, but the selected colour is indicated on the Advanced Colour Selector wheel and triangle. If you try to press and hold the Cntrl key while using the Colour Selector tool, it will not work. This has happened to me before due to my usual habit of using the Cntrl key colour picker.

When you say, "It works fine if I use it by clicking the side ...", do you mean clicking a button on the side of your stylus or do you mean clicking along the white/black/grey side of the colour triangle inside the Advanced Colour Selector?

Changing from grey to light blue (or whatever) should have no effect on any of the tools. They're all just different colours.

When you say, "I have uninstalled krita completely ...", did you also delete the configuration folders and the configuration files before reinstalling Krita?
Depending on your OS, they can be found as indicated in the manual here:

https://docs.krita.org/KritaFAQ#My_reso ... te_them.3F

If you can give more information, it may be helpful in trying to figure out what has gone wrong.

My pen nib just wasn't pushing in properly so it wasn't registering as a click. I'm just a daft wally.
Problem solved