User profile synchronization status is stuck at "Synchronizing" for more that 8 hours and it seems the Active directory import(0) is also not updated.
I ran into this problem a little while ago, the first things to check are to make sure the UPS and UPSS services are started on the server running the sync (Central Admin -> Application Management -> Manage Services on Server). Also make sure you're running Central Admin as administrator or you won't be able to get to this section. The UPSS can take 10-15 minutes to start on some environments, so don't worry if it says "starting" for a while.
I've seen references to Microsoft Forefront Identity Manager service (FIM) preventing sync from finishing, so check to make sure that is enabled, if it is then try restarting it.
Hope that helps!
Its a common issue come. For this type of issue better to understand what is happening back-end. Once we configure UPSync Service in SharePoint, the account from which you configured and trying to provision that trying to make changes in sync DB and parallel trying to start two services 1. Fore Front Identity and Fore Front Service from the APP server. If it got failed to do this then this issue come. So before configuring please follow following steps to configure and provisioning.
Please check followings:
Once you try start again it will start following two services first with same account and then sync will configure properly.
“Forefront Identity Manager Service “& “Forefront Identity Manager Synchronization Service"
*Sync provision take almost 5-10 mins. If taking more then some thing wrong.