Why is my nested while loop not working python?

It's not that it's not doing anything. In fact it's doing a lot, it's in an infinite loop. What happens when a wrong input is entered is:

• p1 = None, p2 = None.
• In the first iteration, since p1 == None evaluates to true, it executes the if statement, a new value is assigned to p1 and now it's not None anymore.
• In the second iteration, p2 == None evaluates to true, it executes the if statement, a new value is assigned to p2 and now it's not None anymore.
• After that, both p1 and p2 are not None, and thus none of the if statements gets executed and the loop iterates infinitely.

I suggest you do the following:

print('''Please pick one of the following:
Rock
Paper
Scissors''')
p1 = None
p2 = None

while True:
    gameDict = {"rock":1, "paper":2, "scissors":3}
    in1 = input("Player 1: ").lower()
    in2 = input("Player 2: ").lower()
    p1 = gameDict.get(in1)
    p2 = gameDict.get(in2)

    while p1 ==None or p2 ==None:
        if(p1 == None):
          val = input("Player 1, please enter one of the choices listed above: ")
          if(gameDict.get(val) != None):
            p1 = val

        if p2 == None:
          val = input("Player 2, please enter one of the choices listed above: ")
          if(gameDict.get(val) != None):
            p2 = val

    print('Done!!')
    print(p1, p2)

Stuff I have fixed:

1. Made a dedicated variable for the input string value, i.e val.
2. Changed elif to if because either of the players' input can be valid, but not the other and you would want to loop until both are valid.

You compare keys entered by the user ("scissors") to the values in the dictionary. You need to ensure that the keys are right:

while in1 not in gameDict:
    in1 = input("Player 1, please...: ").lower()
while in2 not in gameDict:
    in2 = input("Player 2, please...: ").lower()

Once you get valid inputs, you can look them up:

p1 = gameDict[in1]
p2 = gameDict[in2]

i think this is the right code: (you should check if either p1 or p2 is None)

print('''Please pick one of the following:
Rock
Paper
Scissors''')
p1 = None
p2 = None
while True:
    gameDict = {"rock":1,"paper":2,"scissors":3}
    in1 = input("Player 1: ").lower()
    in2 = input("Player 2: ").lower()
    p1 = gameDict.get(in1)
    p2 =gameDict.get(in2)
    while p1==None or p2==None:
        if(p1==None):
            p1=input("Player 1, please enter one of the choices listed above: ")
        elif p2== None:
            p2=input("Player 2, please enter one of the choices listed above: ")
    print('Done!!')
    print(p1,p2)