Stuck on Import/Export screen after System Crash

Sounds like a canadate for resetting the preference file. Resetting the preference file is Adobe speak for deleating the preference file and then letting Lightroom Classic to recreate it.

The preference file can get corrupted, resulting in odd behavior. Some people have a knee jerk reaction in thinking they need to uninstall then reinstall Lightroom Classic, maybe that could be called for, but it would be better to first reset the preference file.

Be aware that resetting the preference file will result in Lightroom Classic creating a new catalog instead if opening your previously opened catalog (normally) so make sure you know where your catalog is. 

Be aware the resetting the preference file will revert some settings in Preferences to defaults. So be aware of what you have changed, so that you can put those back the way you want them.

some links:

https://lightroomers.com/replacing-the-lightroom-preference-file/745/

https://www.youtube.com/watch?v=bARt-hoCc2Q

https://helpx.adobe.com/lightroom-classic/help/setting-preferences-lightroom.html

https://helpx.adobe.com/lightroom-classic/kb/recover-catalog-images-resetting-lightroom.html

What is the "Import/Export screen"?

"I cannot work but do not want to reinstall as this will lose my Collections and Catalog connection" 

Completely incorrect.