Recently my eM Client was not working properly so I uninstalled and installed again but it is now 5 days it is still showing that it is syncing the the mails and folders and I cannot work on it. Does it take this long to sync
Maybe the database is corrupt. Close eM Client then rename the C:\Users_username_\AppData\Roaming\eM Client folder. You may have to show hidden items in Explorer to do that.
When you restart eM Client it will be with a new empty database. Add the account and see how the sync goes.