restarting iPhone

Hello,

Here are the standard steps for a frozen phone:

1. Press and quickly release the volume up button.
2. Press and quickly release the volume down button.
3. Press and hold the side button until you see the Apple logo (could be as long as 30 seconds) 

The timing is a little critical, you may have to try it several times. See this for more detail:

If your iPhone, iPad, or iPod touch won‘t turn on or is frozen

If you want to connect to your computer, you must have a cable. The standard charging cable should work:

If your computer doesn't recognize your iPhone, iPad, or iPod

Good luck.