Baybayin - the lost script
Baybayin is a pre-Hispanic Philippine writing system which is believed to be in used since 14th century, and lost its popularity and eventually ceased existed in the 18th century. The system is a member of the Bhramic family and has had quite a unique setting. Firstly, The system is an abugida system using consonant-vowel combination, and only using this combination. This give a major setback for this system when trying to write modern language. Another interesting points is that, the system only comprises of three vowels: a, i/e, o/u. The whole system can not produce a stand-alone consonant for pronunciation. This system begins with a-row characters, leading to i/e, o/u row. To proceed from 'a' character, we only need to insert certain diacritical mark (Kudlit) to change the sound of the character.
The da/ra row is a special row. As it seems, that does not suggest that da and ra can be used interchangeably, but to replace one another in a circumstance when d is in the middle of two vowels and some other special cases. For more explanation, please use this site: .
Another special note for the system is of the "nga." As we mentioned earlier, the system introduce the consonant-vowel combination, and people might mistakenly think nga does not follow the same rule. But it does, and "ng" is considered one syllable.
To the Filipinos, Baybayin has given the country "its own ancient writing system" as most of Philippine history are covered by Spanish colonization, controls and liberation who bring about changes in language adaption and adoption which result in multiple language usage (Filipino, English and indigenous language). To the surprise, even with lengthy Spanish colonization over this country, very few people of the present speaks Spanish. But Tagalog has been influenced by both Spanish and English. 
There are many question raised, some questions have been answered, specially about the reason of the "lost." Some concerns the responsibility of the Spanish administration over Philippine of the time for the disappearance of Baybayin. But here is the most controversial parts. As Spanish authorities established their power in Philippine during their colonization, they has much intentions to maintain the original objects of the country, maybe including this writing system. We called this system "lost," because we hardly find any Tagalog documents using Baybayin from the pre-Hispanic period and earlier. In addition, there is suggestion that since the Tagalog is more a spoken than a writing,  there is not much record about the history of Baybayin and its continuation until that era. The Spanish, however, has tried to conserve the system and allow the Filipino to sign using this system.
But on the other hand, there are claims that Spanish had destroyed Tagalog Script with Baybayin, to hold protective measure for their religious purpose, as they consider these writings would include spiritual story which would harm their religious campaign in the country. But there is no evidence to this claim, and there is exact theory about the concept behind the destructions of the files, as there is a study which show that the original inhabitants writes on such leaves or bamboos as a letter or a reminder, not a record of any subjects, stories or history. Thus, we may be in the middle of riddles if we continue alleging the Spanish as a destroyer when both facts and theories does not show much supports.
There are a few answers which are acceptable. Most aimed to the system itself, blaming it for not be able to adapt new words from other languages, thus making language progression ceased. It is easy to understand that, with the Baybayin, we can not produce stand-alone character, thus making end-of-word pronunciation very impossible. The theory also says that, as the Spanish whole much powers and developments, people must changed to new environment which would give them hopes and chances to progress also. The Baybayin, which was sited as the nationwide writing system, then, began to lose its popularity due to its limited standard.
Then, there is THIS final question, is it truly "lost?" There is a "yes" and a "no." The "no" side claims that the system has been developed into a new system.  BUT for one thing for sure, the system has been revived but not used. Modern media, education and scientific measure has enable Filipino people, specially students to study more about this system and had it in their heart once again.
To try Baybayin: http://www.baybayin.com/