Statix SC's Code Corrected 3

import pygame
pygame.init()
##########################################################################################
BLACK=(0,0,0)
WHITE=(220,220,220)
BLUE=(0,0,155)
RED=(155,0,0)
YELLOW=(255,255,0)
FPS=30

screenwidth=800
screenheight=800

padding=50
screen=pygame.display.set_mode( (screenwidth,screenheight) )
clock=pygame.time.Clock()

##########################################################################################
class Ball(pygame.sprite.Sprite):
    def __init__(self,x,y,width=20,height=20, color=WHITE):
        super(Ball,self).__init__()
        self.image=pygame.Surface((width,height))
        self.image.fill(color)
        self.rect=self.image.get_rect()
        self.rect.x=x
        self.rect.y=y
        self.dx=1
        self.dy=1

    def move(self):

        self.rect.x += self.dx
        self.rect.y += self.dy

    def update(self, collide=pygame.sprite.Group()):

        self.move()

        if self.rect.right > screenwidth:
            self.dx *= -1
        elif self.rect.bottom > screenheight:
            self.dy *= -1
        if self.rect.left <= 0:
            self.dx *= -1
        elif self.rect.top < 0:
            self.dy *= -1

        collision_list=pygame.sprite.spritecollide(self,collide,False)

        for collide in collision_list:

            # !!!!!!!!!!!!!!!!!
            # So since all you really do when you collide with a paddle is just
            # bounce off it, like reverse the horizontal direction it is going in,
            # you don't really need to test anything, like which direction you are
            # going in or how you are moving. All you need to do is reverse your dx.

            #self.dx *= -1

            # If you want more precise collisions, you can test for the direction you
            # are moving in ( if your horizontal direction is positive or negative )
            # and then match the edge you are on with the edge you are hitting it with.
            # Like this...

            if self.dx > 0: # MOVING TO THE RIGHT, RIGHT SIDE IS WHAT HITS
                self.rect.right = collide.rect.left # Jump to the edge, just for that moment

                self.dx *= -1 # Still bounce
                continue # Get out of this iteration so we don't test for any other edges


            if self.dx < 0: # MOVING TO THE LEFT, LEFT SIDE IS WHAT HITS
                self.rect.left = collide.rect.right # Jump to the edge, just for that moment

                self.dx *= -1 # Still bounce
                continue# Get out of this iteration so we don't test for any other edges


class Paddle(pygame.sprite.Sprite):
    def __init__(self,x,y,width=20,height=150, color=WHITE):
        super(Paddle,self).__init__()
        self.image=pygame.Surface((width,height))
        self.image.fill(color)
        self.rect=self.image.get_rect()
        self.rect.x=x
        self.rect.y=y
        self.movespeed=2
        self.pos=0

    def update(self):
        pos=pygame.mouse.get_pos()
        self.rect.y = pos[1]

##########################################################################################
#PRE LOOP STUFF

ball=Ball(screenwidth/2,screenheight/2-100)
player=Paddle(0+padding, screenheight/2)

active_sprites=pygame.sprite.Group()
active_sprites.add(ball, player)

collision_list=pygame.sprite.Group()
collision_list.add(player)


##########################################################################################
gameexit=False
while not gameexit:

    screen.fill(BLACK)

    for event in pygame.event.get():
        if event.type==pygame.QUIT:
            gameexit=True
            pygame.quit()
    #update functions
    ball.update(collision_list)
    player.update()
    #logic
    #Draw
    active_sprites.draw(screen)
    #delay Frames
    #update screen
    pygame.display.update()

pygame.quit()