User Profile Sync is not Starting in SharePoint 2013

Hello Experts,

I am getting issue with User Profile Sync Service as it is not getting started and hence new users are not getting updated profiles.

Though User Profile is Started and service is running. Following are the steps taken so far:

1. User Profile Sync was stuck in Synchronizing, hence we Stopped. Which later got stuck at Stopped Status. Now it is unprovisioned.
2. IsSynchronizing parameter was true whereas IsRunning was False.
3. We checked the FIM and FIMSync Service, Restarted them. They are getting disabled again.
4. Stopped and Started User Profile and User Profile Sync Service from Services on Server. User Profile is getting started but Sync is stopped again. Once sync service is stopped, in services.msc FIM and FIMSync are getting disabled. 
5. "User Profile Service - User Profile Incremental Synchronization" Timer Job is failing.
6. Did an IIS Reset, nothing worked.
7. Restarted SharePoint Timer Service.
8. There is a Critical level in Log: The Execute method of job definition Microsoft.Office.Server.UserProfiles.UserProfileImportJob (ID 60a32181-84ec-4408-a961-21ba19846541) threw an exception. More information is included below.  Operation is not valid due to the current state of the object. 

Exception stack trace:   
 at Microsoft.Office.Server.UserProfiles.UserProfileImportJob.CreateSteps()    
 at Microsoft.Office.Server.UserProfiles.UserProfileImportJob.Execute()    
 at Microsoft.SharePoint.Administration.SPTimerJobInvokeInternal.Invoke(SPJobDefinition jd, Guid targetInstanceId, Boolean isTimerService, Int32& result)

Any help is appreciated. 

Thanks in advance..

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