This isnt exactly what you asked for but it will get you started.
import os    #bring in the necessary library to access your specific os
filename = raw_input("Enter file: ")   #get user input
dirList = os.listdir('.')    #get the current directory listing
if filename in dirList:      #if the filename sought was in that dirlist....
    print "file found: " + filename   #display it
else:                            #otherwise...
    print "That file does not exist."
solved How can I find a file in a directory [closed]