Drop my iPhone 7 Plus and now when I move it sometimes the screen turns black I have to kept on it or move it for it to go back on?

What could it be the screen or software? I'm scare I'm going to lose my stuff in the phone and I have no money to fix or get a new iPhone so I hope it won't shut off on me completely the screen. What can I do?

This appears to be a hardware issue. It may be an issue with the display itself in which case, it can't really be repaired. It has to be replaced.

If you're scared of loosing your stuff, why haven't you backed them up to a computer or iCloud?