Color Adjustments Options Greyed Out

Got this unexpected issue with the color adjustments greyed out and not available to be used. It worked fine before a few days ago but now it's changed. I've restarted my laptop to see if that was the issue. It didn't do anything. I uninstalled then re-installed Photoshop and it gave me a few other options back (Posterize, Invert and Threshold) but still not the color adjustments. I don't know Photoshop technical stuff and as such I don't know what to do to fix it. I am on the latest version of Photoshop to date.