Yes, by "working correctly yesterday", I mean to say that they were seen fine when I checked it that day.
After checking on Browserstack I get to know that the images work fine on Android devices but aren't displayed on iOS device (Seems to be an iOS problem).
It is to be noted that the image display's fine when I resize the browser window (My site has a responsive design).
The big image seemed to be working fine, but now it isn't.