I have my first daughter who is 7 months old. I kept her name Nailah as per my intuition or my liking towards that name inspite of opposition from my parents and my Wife. Initially my daughter brought me very good luck and fortune, Al-hamdulillaah. But of late things are not working with us properly. Sometimes when I think that I should change his name to Madiha. This thought has benefited 2-3 times. I just wanted to know whether Is this just a superstition or do things of this sort ever happen.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

Naming your daughter Naa'ilah is permissible in principle contrarily to the view of some contemporary scholars who consider that this name is forbidden because it corresponds to the name of an idol that Quraysh used to worship.

Some female companions had this name, like Naa'ilah Bint Ar-Rabee' Ibn Qays, she became a Muslim and she pledged her allegiance to the Prophet and Naa'ilah Bint Sa'd Ibn Maalik also had this name, and had this name been forbidden, the Prophet would have certainly changed it as he changed many names of the companions . Some righteous women of our predecessors also had this name, like Naa'ilah Bint Al-Faraafisah, the wife of 'Uthmaan Ibn 'Affaan .

However, it is not the name of your daughter who brought you good luck and provision, and there is no relation at all between the name and the provision as it is Allaah Alone Who provided you with sustenance, Allaah says (which means): {Is there any Creator other than Allaah who provides for you from the sky (rain) and the Earth? Laa ilaaha illa Huwa (None has the right to be worshipped but He). How then are you turning away from Him.}[Quran 35:3]. Changing the name of your daughter because of what had befallen you is seeing a bad omen. The Prophet said: "An ill omen is a form of Shirk, an ill omen is a form of Shirk." [Abu Daawood] The Prophet further said: "He is not from us, he who sees an evil omen (in something), or this practice is done on his behalf,…'' [At-Tabaraani] The Prophet also said: "Whoever an evil omen prevents him from fulfilling his need, he has indeed committed Shirk." The companions inquired: "How to expiate for that, O Prophet of Allaah?" The Prophet replied: "In order to expiate for this, you have to say: "O Allaah! There is no good except Your Good [that which You made good] and there is no omen except Your Omen, and None has the right to be worshipped except You." [Ahmad]

As regards your saying that it was thinking to change your daughter's name which brought you fortune and the like, then again this is only seeing an omen, and you have to stop doing this, and you should take the means while putting your trust in Allaah. 

Allaah knows best.