How to find all possible four digit combinations of two numbers?

Last night at midnight I decided to change the passcode for my iphone 5, I wanted to make my new passcode 1161 cause I could type it in fast and easily remember it. But I must've typed it in wrong or remembered it wrong cause it says that password is incorrect. I'm stupid. So the passcode is always 4 digits longs and I'm pretty sure the only numbers I used were 1 and 6.So how many different combinations are there of these two numbers, I listed 16 myself but I want to be sure I'm not missing any.
1) 1111
2) 6666
3) 1616
4) 6161
5) 6111
6) 1666
7) 6661
8) 1116
9) 1611
10) 6166
11) 1166
12) 6611
13) 1661
14) 6116
15) 1161
16) 6616

Is this list complete or not? I have a limited number of tries to unlock this so I want to know how many possible combinations there would be and I don't want to delete and restore the iphones memory to get rid of the password because there's stuff on here that I need that is not backed up on my computer.

Yeah I think it's complete, I looked over your numbers for like 10 mins and it seems complete! Have you tried them in your phone?

Yeah. There's on only 16.
but i think that you might have accidentally pressed another number next to 1 or 6. (i don't mean to give you negative thoughts but thats what ususally happens to me)

If only two numbers are used, each of the 4 digits ('slots') have two options either be a 1 or a 6.
Hence there are 2 x 2 x 2 x 2 = 16 total combinations so your list is complete.
A more systematic way of listing would be in increasing order:
1111, 1116, 1161, 1166,
1611, 1616, 1661, 1666,
6111, 6116, 6161, 6166,
6611, 6616, 6661, 6666.

There's 2^4=16 of them. Here they are in lexicographical order:
1 1 1 1
1 1 1 6
1 1 6 1
1 1 6 6
1 6 1 1
1 6 1 6
1 6 6 1
1 6 6 6
6 1 1 1
6 1 1 6
6 1 6 1
6 1 6 6
6 6 1 1
6 6 1 6
6 6 6 1
6 6 6 6

No. Of ways of having 4 sixes=1
no. Of ways of having 3 sixes and 1 one=4!/3!=4
no. Of ways of having 2 sixes and 2 ones=4!/(2!*2!)=6
no. Of ways of having 1 six and 3 ones=4!/3!=4
no. Of ways of having 4 ones=1

adding all the above combinations we get
1+4+6+4+1=16
So congratulations you have listed out all the possible combinations!
just check whether any of them is being repeated!

You have 2 choices for each of 4 digits.
That makes 2x2x2x2 = 16 possibilities.
Yes, there are only 16. It's easier to see if you got them all if you write them in sequence.

I sorted them in Excel and got this list:
1) 11111111
8) 11161116
15) 11611161
11) 11661166
9) 16111611
3) 16161616
13) 16611661
6) 16661666
5) 61116111
14) 61166116
4) 61616161
10) 61666166
12) 66116611
16) 66166616
7) 66616661
2) 66666666

Yes, you got them all.