First, let me explain the normal menstrual cycle:
Ovarian follicles produce estrogen that cause growth of the endometrial mucosa (proliferative phase of the cycle). After ovulation, the yellow body starts to produce the hormone progesterone. Progesterone blocks estrogen (and its growth effect) and prepares the endometrium for implantation of the fertilized egg cell (secretory phase). If there is no fertilization and implantation... the yellow body will stop producing estrogen and progesterone after 14 days. Lack of estrogen and progesterone causes devitalisation and removal of the functional layer of the endometrium. This is manifested with vaginal bleeding called menstruation (period). Menstruation is a regular periodic bleeding because the ovarian function (egg cells development and hormone production) is controlled by the rhythmic function of the hypothalamus.
If there is no ovulation, a yellow body won’t be formed and there will be no progesterone to block the estrogen’s growing effect. So, the endometrial mucosa will continue to grow (proliferate) causing so called "endometrial hyperplasia". This endometrial growing can’t continue forever. At some point, the level of estrogen is no longer enough to support the proliferated endometrium; without progesterone (no ovulation), the existing endometrium begins to desquamate and vaginal bleeding occurs. This bleeding is usually delayed, more abundant, and painless. Sometimes this type of bleeding can become periodic like a normal menstruation; in that case, it is called "pseudo-menstruation".