Reading and Writing Primenumbers

def primenumbers_brute():
    #Thanks to http://stackoverflow.com/questions/21487846/basic-prime-number-generator and http://scratch.mit.edu/projects/978284/
    x = 0
    j = 2
    chk = 1
    f = open("primes.txt", "a")
    primes = []
    notprimes = []
    ask = raw_input("how many primes? ")
    start_time = round(time.time())
    last_time = round(time.time())
    pmf = 0
    fr = open("primes.txt","r")
#    with fr as fr:
 #       primes = fr.read().splitlines()
    for line in fr:
        primes.append(line)
    print(primes)
    if not(primes[-1] == "") and not(primes[-1]==2):
        j = int(primes[-1])
#    while len(primes)<int(ask):
 #       k = 2
  #      while not(j%int(primes[x])==0) and not(j==k):
   #         k = k+1
    #        if
     #   if j%int(primes[x])==0:
      #      j=j+1
       #     x = 0
        #elif int(primes[x])>j/2:
         #   j = j+1
          #  x = 0
#        elif not(j%int(primes[x])==0) and int(primes[x])<j and not(j in primes):
 #           primes.append(j)
  #          f.write(str(j) + "\n")
   #     if len(primes) >= 1000*chk:
    #        elapsed_currenttime = round(time.time() - last_time)
     #       last_time = round(time.time())
      #      elapsed_starttime = round(last_time - start_time)
       #     chk = chk + 1
        #    print("There have been " + str(len(primes)) + " primes counted so far, " + str(elapsed_currenttime) + " seconds since the last message and " + str(elapsed_starttime) + " seconds from the start of the calculations.")
    while len(primes) < int(ask):
        pmf = 0
        k = 2
        while not(k==j) and not(j%k==0):
            if pmf == 0:
                k = k+1
                pmf = 1
            else:
                k = k+2
        if k == j:
            primes.append(j)
            f.write(str(j)+"\n")
        else:
            notprimes.append(j)
        if len(primes) >= 1000*chk or time.time()-start_time()%60==0:
            elapsed_currenttime = round(time.time() - last_time)
            last_time = round(time.time())
            elapsed_starttime = round(last_time - start_time)
            chk = chk + 1
            print("There have been " + str(len(primes)) + " primes counted so far, " + str(elapsed_currenttime) + " seconds since the last message and " + str(elapsed_starttime) + " seconds from the start of the calculations.")
        j = j + 1
        if j % 2 == 0:
            j = j + 1
        else:
            j = j
    print("Primes written to file 'primes.txt', " + str(len(primes)) + " written in " + str(round(time.time() - start_time)) + " seconds")
    f.close
    return(" ")