How do I get my music player to choose an mp3 file and play it?

I'm having trouble making the program choose the music and play the selected music

from tkinter import *
from tkinter import messagebox
from tkinter.filedialog import askopenfilename
from pygame import *
from pygame import mixer
jan = Tk()
jan.title("JANELAA")
jan.geometry('400x400')

class Sistema:
  def __init__(self, box):
    self.frame = Frame(box)
    self.frame.pack()
    self.menu = Menu(box)

    self.menuFile = Menu(self.menu)
    self.menuFile.add_command(label="Notepad" , command=self.note)

    self.menu.add_cascade(label="File", menu=self.menuFile)

    self.menuMusc = Menu(self.menu)

    self.menuMusc.add_command(label="|Play|", command=self.play)
    self.menuMusc.add_command(label="|Pause|", command=self.pause)
    self.menuMusc.add_command(label="|Retomar|", command=self.unpause)
    self.menuMusc.add_command(label="|Parar|", command=self.stop)
    self.menuMusc.add_command(label="|Escolha|", command=self.escolher)
    self.menu.add_cascade(label="Musicas" , menu=self.menuMusc)
    self.menuOption = Menu(self.menu)
    self.menu.add_cascade(label="Options" , menu=self.menuOption)
    box.config(menu=self.menu)









def note(self):
    textField = Text(jan, width=300)
    textField.pack(side=LEFT, expand=True, fill='both')
    scrollBar = Scrollbar(jan)
    scrollBar.pack(side=RIGHT, fill=Y)
    scrollBar.config(command=textField.yview)
    textField.config(yscrollcommand=scrollBar.set)

    def salvar():
        name = filedialog.asksaveasfile(mode='w', defaultextension=".txt")
        t =textField.get(0.0, END)  # Pega o texto do textField
        name.write(t.rstrip())  # Escreve o texto no arquivo criado

    bt = Button(jan, text="Salvar", command=salvar)
    bt.place(x=360 , y=0)





def play(self):
        mixer.init()
        mixer.music.load('coldb.mp3')
        mixer.music.play(1 , 1)
        musica_tocando = True
        while mixer.music.get_busy():
            time.Clock().tick(10)
            for event in event.get() :
                if event.type == MOUSEBUTTONDOWN:
                    if musica_tocando: 
                        mixer.music.pause()
                        musica_tocando = False
                    else:
                        mixer.music.unpause() 
                        musica_tocando = True


def pause(self):
         mixer.music.pause()         

def unpause(self):
        mixer.music.unpause()

def stop(self):
        mixer.music.stop()

def escolher (self):
   selecionar = askopenfilename(initialdir="C:/Users/%user%/desktop",
                      filetypes =(("Arquivo de audio", "*.mp3"),("All Files","*.*")),
                      title = "Selecione as musicas"
                      )
   if selecionar == '': # Se tiver '' ele não faz nada ( pass )
       pass
   else:
       mixer.music.load.append(selecionar)





jan.wm_resizable(0, 0)
Sistema(jan)
jan.mainloop()