Fixing Text Storing/Loading

You should write each list from get_user_list with a new line generally when storing as text. Also note you don't need to call f.close() when using with as it closes the file for you when it is no longer needed.

with open(str(epoch_time) + '_intercom_Users.txt', 'w') as f:
    for item in get_users_list:
        f.write(f"{item}\n")

This will allow each item to be read in separately and not have to deal with trying to split up your string later.

Then when you go to read you will have a string representation of a list on each line. You need to do a literal eval and remove your new lines characters as well. You can do this in one list comprehension.

import ast

with open('1556640109_intercom_Users.txt', 'r') as f:
    x = f.readlines()   # read into a list
    x = [ast.literal_eval(x[i].rstrip('\n')) for i in range(len(x))]

It would seem like you don't need the \n since we add it then remove it, but it's an easy way to make each item remain a separate item. Without that you would need to add a separator and read in the single line then do a .split(). Using this method will allow you to read the data at rest easily and read it back in easily as well.

Using Pickle Instead

As others have noted, this isn't a great way to do data serialization which is what it appears you are doing. Python comes preloaded with pickle which can serialize and store any Python data type as is and then read it back it.

You could use it like:

import pickle

def get_users():
    counter = 0
    for i in users_intercom:
        get_users_list.append(users_intercom[counter].split())
        counter = counter + 1

        if counter > 100:
            with open(str(epoch_time) + '_intercom_Users.pickle', 'wb') as f:
                pickle.dump(get_users_list, f)
            break

And then read it again:

with open('1556640109_intercom_Users', 'rb') as f:
    x = pickle.load(f)

with open('C:/path/numbers.txt') as f:
    lines = f.read().splitlines()

this will give you a list of values (strings) you had in your file, with newlines stripped.

In Python 3.5+, you can also do:

lines = pathlib.Path('C:/path/numbers.txt').read_text().splitlines()

also, watch your backslashes in windows path names, as those are also escape chars in strings. You can use forward slashes or double backslashes instead.

Read a specific item in index i:

item = L[index]

Read a sequence of items from index 'start' to index 'stop':

seq = L[start:stop]

Iterate over a list:

for item in L:
    print item

If you need both the index and the item, use the enumerate function:

for index, item in enumerate(L):
    print index, item

You can also get the reversed list:

L.reverse()

Get list length:

length = len(L)

And there are so much more operations you can perform on lists.