Determine, analyze stuck pixels and try to fix them(sorry dead pixels are dead :))
If a stuck pixel occurs on your LCD or OLED display, there might be still a chance to somewhat unstuck that. But if the pixel is really dead i.e. has a hardware failure, there isn't anything you can do.
Here is an good software to determine if your pixel is stuck or dead.
On older Ubuntu systems there was a program called LCDNurse it seems that this project is gone for good :(
But there is still hope, there is a neat web application called jscreenfix
You could try this tool, begin with 10 minutes and hope for the best if this fails. You can go for 15 minutes. If this also fails, you could go for 8 hours. I know, sounds like a little overkill. But who knows ¯_(ツ)_/¯ Good luck. :)
Further reading:
https://www.hecticgeek.com/lcdnurse-stuck-pixel-ubuntu-linux/
https://www.jscreenfix.com/ https://www.whitescreen.org/ an alternativ to this jscreenfix
https://www.wikihow.com/Fix-a-Stuck-Pixel-on-an-LCD-Monitor#step_2_1
http://www.lagom.nl/lcd-test/ A good resource for LCD test images http://www.lagom.nl/lcd-test/all_tests.php#angle_red
https://www.lifewire.com/what-is-a-pixel-1846929
https://community.medion.com/t5/General-Technical-Knowledge-Base/Pixel-Fault-Classes/ta-p/80460
https://en.wikipedia.org/wiki/ISO_9241#ISO-9241-302,_303,_305,_307:2008_pixel_defects