Brief Answer:
Your decrease libido is because of menopause.

Detailed Answer:

Hello,

You have not asked any specific question, so I will explain your whole concern.

Decrease of libido means decrease in sexual desire. There are many causes for that.
In your case, most appropriate cause seems to be menopause.

After women enter into menopause stage, her female hormones especially estrogen start decreasing. This is because ovary getting shrinking after menopause.

The depression and anxiety also associated with decrease sexual desire. So it can be ruled out as well.

You can try to take vegetables and fruits more. You can take soy, chick peas, black beans etc that can be beneficial as they contain phytoestrogen.

In some patients a low dose hormone replacement therapy can be given.

Hope I have answered your question.
Let me know if I can assist you further.
Best regards.

---