My girlfriend had the essure procedure done and 4 years later she has no period. she took a hpt and the first one was negative the second was positive and the last two where done at the her ob/gyn, and they where negative. what is causing this?

The Essure does not effect periods so it seems more likely that her periods are becoming less regular as she gets older. Her Ob/Gyn should have evaluated her for other possible problems and pregnancy has apparently been ruled out. She probably then had a false positive HPT, which are rare but not unheard of.

I don't know what the "essure procedure" is, but I assume your girlfriend (if her age is similar to yours) is menopausal with one false positive HPT. An examination and further testing by a trusted ob-gyn should provide the answer to your question.