Welcome to Rootschat. Gilroy1790 hasn't been online since 2012 but hopefully they will see your message and reply.
Meanwhile, a few bit of general information for you.
The majority of records destroyed were census records (some pulped during WWI), Church of Ireland registers and Wills (pre-1900ish but more on this in a minute).
The existance of church records depends on the religion and the individual church, and also how well the clergyman kept records. Once you know where a family might have lived then you can check to see what church records for that area survive. PRONI, Belfast have an extensive collection on microfilm but if you have any queries about any particular ones just ask.
*PRONI also have a large collection of Wills, the volumes which recorded probate and administration details and, in the case of pre-1900 Wills, microfilmed copies of the Will Books (wording of the Wills copied by clerks into ledgers) but if there was no Will there will only be the indexed entry. PRONI have put the Will extracts online (covering probate for Armagh, Belfast and Londonderry).
The first complete census for Ireland is 1901- it and 1911 are online (free) on National Archives, Dublin website. For earlier years only small fragments survive- the 1831 for Co. Londonderry does but it only lists head of household, number of males & females and religion.