Hi there and welcome
Can you tell me please what you have already done to try to resolve this?
The issue is either the battery or the firmware. To confirm which, we will need to reinstall the phone.
this will remove all data from it and return it to new, but we cannot avoid this.
To do the reset
Set it up and tell me please how the battery now functions.
They should be saved online, if you sign in at www.outlook.com and sign in with the same account as on the phone, then click on the 9 dots, top left the people, do you see the contacts?
Its automatic, when you set up the phone, you put in your email address and it will then synch it for you
Thank you and your most welcome!
press and hold the icon until you activate it. choose Pin to Start