WhatsApp is stuck at initialzing Restored phone to original factory settings on 22nd November 14.Today I downloaded WhatsApp from the Play Store(and it installed correctly). 

After entering the phone number, WhatsApp has been stuck at the Initializing screen. I tried clearing the Application data. Reinstalled the app but to no avail. It's been stuck at the initializing screen for 2 hours now. Installing via the APK didn't help too.

I'm using a Samsung Galaxy S3 and have 4170 contacts (could that be the why the reason why sync is taking so much time?).
Yeah the 4170 contacts is the thing because of which it's taking so long. What I'd suggest is, try removing your Google Account(after syncing everything ofcourse) so that contacts are removed and THEN try starting WhatsApp.

Enter your number with no contacts and let it initialize. That should fix the problem. After WhatsApp is running just log into your account and resync contacts to phone and WhatsApp.