Hi, I'm trying to make a catching game. How do I reset the score is a sprite misses the other?

Also, How do I add a screen with the score and a restart button?

I'm assuming you are using this tutorial. If you aren't, you might want to check it out.

When the sprite hits the bottom and goes back to the top, you can use ‘set score 0’ to reset the score. Alternatively, you can make the game end. To do this, you will want to use a broadcast so the button knows to appear.

What you'll end up with could look something like this:

when green flag clicked
broadcast [Start Game v] // Tell everything to start

when this sprite clicked // In the button
broadcast [Start Game v] // Tell everything to start

when I receive [Start Game v] // In the button
hide // We don't want it to get in the way during the game

when I receive [End Game v] // In the button
show // We need to see it to click it

when I receive [Start Game v] // In the ball / sprite being caught
forever
if <touching [Catching v] ?> then 
change [Score v] by (1)
go to [random-position v]
else
if <(y position) < [-150]> then
 broadcast [End Game v] and wait // Tell the button to appear
 stop [All v] // Stop the game
end
end