The Quicken Won't Open problem could appear as a result of a recent product update. It's possible that an installation issue is a reason for Quicken's failure to run. Restarting the computer will soon solve this issue.
Important: Quicken should not be used with network or shared drives (such as OneDrive or Google Drive). Although data files can be backed up to a network, Quicken shouldn't be accessed or utilized remotely. Make sure Quicken is installed on your computer's hard drive.