Default [Q] Need help to restore data

Hello
I have the HTC One M7 International unlocked edition(Indian version) 32GB. I had given my phone for camera replacement under warranty as I had the purple tint camera issue. I had done a complete back-up and synced my phone using HTC Sync Manager. My laptop(Macbook Air) had some storage issue and the back-up got deleted. I had taken several photos and videos in April and May but they seem to have vanished from my back-up. The back-up has photo albums of March 2014 and before. I had done several back-ups in May itself but they seem to have gone. The service centre people had factory reset my phone.

Is there any way that i can retrieve my data as there were some pretty important photos I had taken? Please any help will be appreciated.

My phone is running on Android 4.4.2 and is unrooted. I had used HTC Sync Manager v3.0.28.