Also we are unable to create shareable link for my recently uploaded videoes .
What happens when you try? Are you getting an error? Best guess, since both your existing links stopped working and you can't create new ones, would be that you're ability to share has been disabled by Dropbox. You'll need to contact Support for assistance.
I'm having adult site, and some content I have recently uploaded on my site they work fine but now they say error called Html 5 video not found (but video is already their). Also in your blog I saw that you support adult site, also we use dropbox since we getting all that features which are making us to use it but now we are getting irretating since we are getting lots of reports on our email from user that they didn't access video