Starting from the beginning the Python code when we have arbitrary user input

How to start the code from beginning to check again the user input:

Here user can choose minus value to and positive value but not 0 and 1.

What should I do to start the code again for another input if user write 0 or 1?

inp  = float(input("PLEASE ENTER VALUE: "))
for xx in range(1,820):
    A = dfimppara.iloc[xx, 1]
    B = dfimppara.iloc[xx, 2]
    lim = Ju - Jl
    if inp<0:
        if lim > 1:
            pass
        else:
            print('You are calculating the entire possible J')
            print('ans=',A,'-->', B,'Tex =', ET(xx))
    if inp==0 or inp==1:
        #I want the code to start at beginning to use another inp
    else:
        if Ju==inp:
            print('ans=',A,'-->', B,'Tex =', ET(xx))