screen sometimes not working

See this support article:--> Get help with the display on your iPhone, iPad, or iPod touch - Apple Support

If you get no improvements, contact Apple support or have your device inspected at an Apple Store.

Regards

Giulio

Sorry about that, but we (just users like you) can't help you remotely, except offering the support article I already posted.

Try to click on "contact support" on the top right corner of this page.

Regards

Giulio