One of the most famous myths about Ishtar describes her descent to the underworld. In this myth, Ishtar approaches the gates of the underworld and demands that the gatekeeper open them:
If thou openest not the gate to let me enter,
I will break the door, I will wrench the lock,
I will smash the door-posts, I will force the doors.
I will bring up the dead to eat the living.
And the dead will outnumber the living.
The gatekeeper hurried to tell Ereshkigal, the Queen of the Underworld. Ereshkigal told the gatekeeper to let Ishtar enter, but "according to the ancient decree".
The gatekeeper lets Ishtar into the underworld, opening one gate at a time. At each gate, Ishtar has to shed one article of clothing. When she finally passes the seventh gate, she is naked. In rage, Ishtar throws herself at Ereshkigal, but Ereshkigal orders her servant Namtar to imprison Ishtar and unleash sixty diseases against her.
After Ishtar descends to the underworld, all sexual activity ceases on earth. The god Papsukal reports the situation to Ea, the king of the gods. Ea creates an intersex creature called Asu-shu-namir and sends him-her to Ereshkigal, telling him-her to invoke "the name of the great gods" against her and to ask for the bag containing the waters of life.
Ereshkigal is enraged when she hears Asu-shu-namir's demand, but she has to give him-her the water of life. Asu-shu-namir sprinkles Ishtar with this water, reviving her. Then Ishtar passes back through the seven gates, getting one article of clothing back at each gate, and is fully clothed as she exits the last gate.
Here there is a break in the text of the myth. The text resumes with the following lines:
If she (Ishtar) will not grant thee her release,
To Tammuz, the lover of her youth,
Pour out pure waters, pour out fine oil;
With a festival garment deck him that he may play on the flute of lapis lazuli,
That the votaries may cheer his liver. [his spirit]
Belili [sister of Tammuz] had gathered the treasure,
With precious stones filled her bosom.
When Belili heard the lament of her brother, she dropped her treasure,
She scattered the precious stones before her,
"Oh, my only brother, do not let me perish!
On the day when Tammuz plays for me on the flute of lapis lazuli,
playing it for me with the porphyry ring.
Together with him, play ye for me, ye weepers and lamenting women!
That the dead may rise up and inhale the incense."
Formerly, scholars believed that the myth of Ishtar's descent took place after the death of Ishtar's lover, Tammuz: they thought Ishtar had gone to the underworld to rescue Tammuz. However, the discovery of a corresponding myth about Inanna, the Sumerian counterpart of Ishtar, has thrown some light on the myth of Ishtar's descent, including its somewhat enigmatic ending lines.
According to the Inanna myth, Inanna can only return from the underworld if she sends someone back in her place. Demons go with her to make sure she sends someone back. However, each time Inanna runs into someone, she finds him to be a friend and lets him go free. When she finally reaches her home, she finds her husband Dumuzi (Babylonian Tammuz) seated on his throne, not mourning her at all. In anger, Inanna has the demons take Dumuzi back to the underworld as her replacement. Dumuzi's sister Geshtinanna is grief-stricken and volunteers to spend half the year in the underworld, during which time Dumuzi can go free.
The Ishtar myth presumably has a comparable ending, Belili being the Babylonian equivalent of Geshtinanna,
Found at: Wikipedia