I cracked my iPhone screen - 1

I tried switching it off and on but it won't help.

How would switching it on and off fix its crack?

You can't fix a crack by turning it off and on.

Dude, you cracked your iPhone. That isn't something that you can fix by restarting your iPhone… In fact, the only possible way to get it fixed is by going to an Apple store and getting a new one.