Why are the apps not showing up after Windows 10 technical preview update?

[Windows Central Question]

I updated my Lumia 730DS today. It took around 1 hour for the update to complete on Fast Ring. After the update, the phone restarted and was migrating the data. But the phone got switched off because of low battery while migrating data. On charging again, the phone restarted but I'm not able to access most of the apps, not even settings.