My canvas is stuck in grayscale

If you can’t select any color on your canvas with the eyedropper tool, your color profile may set be to grayscale. Procreate adopts the color profile of any image imported into the Gallery. You may have imported an image with a Grayscale profile.

To use colors again, create a new canvas with an RGB or CMYK color profile. You can bring a grayscale image or layers into this new canvas and it will remain in the correct color profile.