Start by running the Windows Store Apps troubleshooter.
Open Start > Settings > Update & security > Troubleshoot
Scroll down to the bottom
Click Windows Store Apps
Click Run the troubleshooter
When complete try opening the Store again.
Also check if the Store works in another user account.
Press Windows key + R
Type: wsreset.exe
Hit Enter
Do this a couple times then try launching the Store again.
Your Antivirus might be interfering with the Store, try disabling it 'temporarily' to see if it launches.
Check Windows Update and install the latest updates. Sometimes Microsoft releases infrastructure fixes for the Store through Windows Update.
You can also try resetting the store app using the following instructions:
https://www.groovypost.com/howto/reset-windows-...
If that does not work, try resetting the software distribution folder:
Before carrying out this procedure, disconnect from the Internet. That means turning off Wi-Fi and disconnecting from a wired connection. If you don't, Windows 10 will indicate some files are in use and cannot be modified or the command will be non-responsive. Also, you should restart your computer after disconnecting from the Internet. The easiest way to do it is to enable Airplane mode from the Action Center - Windows key + A.
1. Open Start, type: CMD
Right click CMD
Click Run as administrator
Type each of the following then hit Enter
taskkill /F /FI "SERVICES eq wuauserv" (do this multiple times)
net stop cryptSvc
net stop bits
net stop msiserver
ren C:\Windows\SoftwareDistribution SoftwareDistribution.old
rmdir C:\Windows\SoftwareDistribution\DataStore
rmdir C:\Windows\SoftwareDistribution\Download
When complete, hit Enter, then restart, then try updating again.