Read .txt file and sum numbers exercise HELP

[Akhaylin]

I am tasked with this excercise:
Edit the Python file processData (or use it as a guide when you create a new Python file) so it
reads in the data from population.txt, checks to make sure the file exists and is in the right
format (if it isn’t throw an appropriate exception), calculates the combined population of the
countries in the text file and prints that total.

however am stuck as my code will mot print total and will only change .txt file please help

This program processes a file containing a count followed by data values.

If the file doesn't exist or the format is incorrect, you can specify another file.

#

def main() :
   done = False
   while not done :
      try :
     filename = input("Please enter the file name: ")
     data = readFile(filename)

     # As an example for processing the data, we compute the sum.
     total = 0
     for value in data[:5]:
        total = total + value

     o=open("output.txt","w")
     o.write("The sum is "+ str(total))
     done = True

  except IOError :
     print("Error: file not found.")

  except ValueError : 
     print("Error: file contents invalid.")

  except RuntimeError as error :
     print("Error:", str(error))

Opens a file and reads a data set.

@param filename the name of the file holding the data

@return a list containing the data in the file

#

def readFile(filename) :
   inFile = open(filename, "r")   
   try :
  return readData(inFile)
   finally :
      inFile.close()

Reads a data set.

@param inFile the input file containing the data

@return the data set in a list

#

def readData(inFile) :
   data = []
   for line in inFile:
      line =line.split(":")
      value = int(line[1])        # May raise a ValueError exception.
      data.append(value)

Make sure there are no more values in the file.

  line = inFile.readline()
   if line != "" :          
  raise RuntimeError("End of file expected.")
   return data

Start the program.

   main()