First of all, at 38 years old, your chances of having endometrial (or uterine) cancer are extremely low, and second of all, the fact that you are no longer having your period and experiencing pain are not usual symptoms of cancer. It sounds like this is a major concern of yours, so I would like to just help you to feel more relaxed that this very unlikely.
If you had a partial hysterectomy, this is also referred to as a subtotal or supracervial hysterectomy which means that the entire uterus is actually removed, leaving the cervix behind. This is in contrast to a total hysterectomy in which the cervix is also removed. It sounds like there may have been some confusion regarding exactly what the procedure that had been done was - because with a partial hysterectomy, since the uterus is removed, after the surgery, you should not menustruate anymore. Since the ovaries are left intact, you will still experience normal hormone levels, but will not experience monthly bleeding. I am attaching a link for you to learn more: http://www.womentowomen.com/hysterectomyandalternatives/vaginalandpartialhysterectomyoptions.aspx
If, however, the procedure was a D&C or dilation and curretage - and not a partial hysterectomy, in this case the lining of the uterus was scraped to remove polyps or other sources of bleeding - then you could have a different problem, also a common complication, called Asherman's syndrome which is the formation of adhesions after the procedure causing you to stop menstruating normally as well, and a common cause of pain. Here is a link with more information about this: http://www.nlm.nih.gov/medlineplus/ency/article/001483.htm
It sounds like the most important thing you can do is clarify exactly what the procedure was that was done, because if it is the first situation, it is completely normal that you do not have your period - and now the cause of the pain will need to be investigated; whereas if the situation is the second, you should be able to recover menstrual bleeding and relieve the pain by a surgical procedure to release the adhesions.
I hope this is helpful and please let me know if I can answer any more questions.