Nefila is when a person falls from his spiritual level.

Unavoidable A person has to pass through many descents before he is able to permanently enter the Gates of Holiness and be able to properly and consistently keep the Torah.[2] Even all the Tzadikim and G-D fearing individuals had to pass many obstacles and tests before the reached the a level where they remained properly strengthened.[2] Diagnosis When a person has a Nefila he often looses the excitement and energy that he had regarding the various aspects of Avodas Hashem.[1] In more sever cases of a Nefila a person starts to stray away from Judaism and good deeds. A person might also fall into various levels of atheism and impure thoughts.[1] Confusion Often a person experiencing a Nefila will go through various levels of confusion and confoundment, this is because these impure and atheistic thoughts are a manifestation of the Klipot and these surround a persons heart causing him much crookedness and confusion.[1] Mekomos HaMitunafim If term used to describe the state of a person that had an extreme Nefila.[1] Emerging It is very hard to emerge from low levels of Nefila since it is very hard to find Hashem there.[1] However if a person truly binds himself to a True Tzadik it will awaken him even in the worst descents to return to Hashem. [1] Another method of ascendance is employing the Ayeh technique. Since a person can not perceive Hashem, he should yell 'where is Hashem. Meaning; he should pray and plead to Hashem about his great distance from the Truth.[1]

[1] Eitzos Mevoaros- Hischazkus #30 [2] Eitzos Mevoaros- Hischazkus #32