The letters ء ، و ، ی are called حروف عللت /weak letter, so these letters can be changed with each other (read about it here :-http://sheepoo.wordpress.com/2008/01/28/sarf-the-rules-for-تَعلِیل-a-look-at-اجوف-and-ناقِص/)
The word Quran can be derived either from
ق ر و
ق ر ء.
Derived from ق رء it will have the meaning of reading, collection,
The word Quran from ق ر ء made under the paradigm فعلان which is an adjective will give the meaning thereby a writing which is read/consulted extensively.
Lughat ul Quran by llama Parwez
Used as a subst., and unrestricted, it is applied in the language of the law to the substance itself and lexical to the alphabetical letters [in which it is written] for these are what are read;”
The original meaning of the word is the collection and that the قُرْآن is so called because it has collected the stories [of the messengers/reformers ], and commands and prohibitions, and promises and threats, and the آيَات [i.e verses, or signs], and the سُوَر [or chapters]”
So the Quran is in relation to the content and collection of the dossier. IE The قُرْآن is the components that make up the document.
He collected together the thing, put it or drew it together, part to part or portion to portion
You derive from ق رو it will mean era or period
But if it is made in dual form of a noun then it is made by adding ا ن to the noun. For example قلم is singular, but if you add ا ن to قلم then قلمان will mean two pens
The same way if you say the word قرو then it will mean one period or era, but if you add ان to قرو then it will become قروان. Now as explained earlier ء , و and ی are interchangeable so قروان is changed to قرءءن which is written as قرآن and it will mean the description of two eras i.e. era of Islam and Kufr. · Updated about 4 years ago
Notes on the (Quran) collection:
 the stories [of the messengers/reformers ],
 commands and prohibitions,
 promises and threats
 the آيَات [i.e verses, or signs]
 the سُوَر [or chapters]