Settings disappeared!

[Windows Central Question]

Hi, recently my settings and a few other apps have disappeared. It started when my battery died, so I fully charged it then turned on my phone, I went to find settings and it had disappeared, also a few installed games I had disappeared. I tried going onto Cortana and Microsoft Edge but it didn't enter the app. When I try to download any app from the Store, it repeatedly says 'Just a moment...' on the screen, then it says 'Try again later. Something happened at our end.'

-Nokia Lumia 735