Iphone6 decided to set itself in "hello" screen mode.

Hello!

Yesterday i experienced something very strange. I was out and wanted to check if I had any msgs or calls and my iphone set itself to "hello" screen mode. I dont know why this happened. It was within some minutes, because I had been using the phone all day normally without any problems.

Now i don't know what to do and how to make it work. I don't want to set it up as a new phone as all data will be lost. iCloud i do not use and the backups i have on my pc are old ones without all the new data. I was on a business trip and couldn't also do a backup. Now i ****** and frustrated as the data is needed for business purposes.

Can somebody help me out?

Thanks in advance!