My iphone14 wont start or charge, the screen is black

• Charge for 30 minutes (even if it doesn’t show)
• Press and quickly release VOLUME UP
• Press and quickly release VOLUME DOWN
• 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.

You’re welcome. That is called a “Forced restart” - it’s the iOS equivalent of turning your computer off with the power switch, then turning it back on. Essentially it is a “reboot”.