rearrange set of items randomly

Dear all,
I hope that this question is not too weird, I will try to explain it  
as good
as I can.

I have to write a function for a school project and one limitation  
is that I
may not use the in built function sample()

At one point in the function I would like to resample/rearrange the  
items of
my sample (so I would want to use sample, but I am not allowed to do  
so), so
I have to come up with sth else that does the same as the in built  
function
sample()

The only thing that sample() does is rearranging the items of a  
sample, so I
searched the internet for a function that does that to be able to  
use it,
but I cannot find anything that could help me.

Can maybe someone help me with this?
I would be very grateful,