macbookPro 16" Sonoma OS. Everything was OK until, under accessibility, I increased the contrast and it became stuck on the max amount, can't even see the slider any more. I have restarted which didn't work. I would appreciate any suggestions. Thank you.
[Re-Titled by Moderator]
MacBook Pro (2017 – 2020)
Yes, it can be nearly impossible to see the slider when contrast is set to maximum.
Two ideas:
a) Try to grab it, anyway. It still works, just so long as you click on the right spot
b) Change mode from Light to Dark - in Dark mode, the slider is still visible, you can drag and then, if you want, you can switch to Light mode again.
Re: "high contrast stuck: Macbook Pro 16": Sonoma OS": "can't even see the slider any more"
Try:
Apple menu 
> System Settings, click Accessibility 
in the sidebar, then click Display on the right. (You may need to scroll down.)
In the list of options look for: "Increase contrast"
Hope you can change the setting :-)
Else:
If needed: How to contact Apple for accessibility support - Apple Support
High contrast stuck on my MacBook Pro
