I need my photos and videos in my iphone which is not turning on

If you don't have a recent backup of thos pics/videos and if you do not use iCloud Photos sync, those media are at risk.

If this is the case, and if it is a matter of battery, make an appointment (*) and have your battery replaced at an Apple Store or AASP (Apple Authorized Service Provider) among this list:--> https://locate.apple.com/choose-country-region . EXPLAIN your concerns (of not having a backup) to the technicians. They will do their best (with no garantee that your media will remain on your iPhone).

Regards and best of luck.

Giulio

(*) You can do it:

• Online:--> Genius Bar Reservation and Apple Support Options - Apple;
• Contacting a local Apple Store or AASP among the list provided above;
• Using the "Apple Store" app, available and downloadable from AppStore.

You can’t. That’s what backups are for, and they must be done before disaster strikes; after is too late.

Can you plug in the phone, then while plugged in try a forced reset?

• Press and quickly release VOLUME UP

     then

• Press and quickly release VOLUME DOWN

     then

• Hold the SIDE button until an Apple logo appears (15-30 seconds), ignoring "slide to power off" if it appears

The operative word here is QUICKLY; and try it a couple of times, the timing is a little tricky.