Windows Security Wont Open

Check Windows Update, Update History, see if you just got an update. If you did, roll it back and see if that fixes the problem.

Settings, Update & Security, Vieew Update History.

If one was installed toady or in the last day or two, click on Uninstall Updates at the top and select the new update then right click on it and select Uninstall.

Is Microsoft Defender Antivirus service running?

Other suggestions,
- run quick check with AdwCleaner,
- restart in clean boot and check if you can start security there

Check for updates yourself.

Norton Update Center

Have you tried running DISM and SFC? Here is a batch file I use:

Copy and paste into a batch file. I call it DISMandSFC.bat

Code:

@echo off
Rem
Rem Run the following commands in sequence. If any fail run again up to 3 times. 
Rem See if you can get all 3 to run without error:
Rem Dism /Online /Cleanup-Image /StartComponentCleanup
Rem Dism /Online /Cleanup-Image /RestoreHealth
Rem SFC /scannow
Rem
date /t & time /t
echo Dism /Online /Cleanup-Image /StartComponentCleanup
Dism /Online /Cleanup-Image /StartComponentCleanup
echo ...
date /t & time /t
echo Dism /Online /Cleanup-Image /RestoreHealth
Dism /Online /Cleanup-Image /RestoreHealth
echo ...
date /t & time /t
echo SFC /scannow
SFC /scannow
date /t & time /t