Why can’t I open any apps on iphone?

I am going to assume that you have an iPhone with a Face ID since you did not reveal which iPhone you have and recommend the following resolution to try-

Try and Force Restart your iPhone exactly as shown below and see whether that resolves the issue:

• Press and quickly release Volume UP button
• Press and quickly release Volume DOWN button
• Press and Hold the SIDE button until an Apple logo appears and then release the Side button (Can take up to 20 seconds. (DO NOT release Side Button when invited to Slide Power OFF). 

Axel F.

You are welcome.

Axel F.