The Myers Briggs test is supposed to be done with contact with a trainer, so that the results can be interpreted correctly and understood.
This page gives more information about the test:
Myers Briggs explained
There is also a Jung-Myers-Briggs test online which you can take. Some of the wording of the questions may seem a bit ambigous or repetitive, and it's best not to think too hard about each one.
Online test
I did this and it came out fairly similar to the last one I did so I think it must be reliable.