If these steps didn't work, let's perform a mini-repair by restarting your computer to clear these processes and temporary data in your system file. Then, try to re-open QuickBooks. If you receive errors when opening your QB Desktop, I'd suggest you run the QBInstall tool. Here's how:
Close any open programs, then run the QBInstall Tool. This process may take a while to complete, depending on your internet speed and computers' performance.
Restart your computer after running the tool. This is to ensure all parts are properly updated.
If none of these steps works for you, I'd recommend performing a clean install. No worries, this action will not remove your company file. Your installation and program files will just be moved into a new folder in the same default location.
For more information, check out this help article: Clean install QuickBooks Desktop. It has a step by step guide to help you completely uninstall QB Desktop to fix company file issues.