I would like to ask for any advice with the following:

There are two DBs in my Sybase server and both of them have a user called USER. Recently I realized that the DB_2 contains only system tables and user procedures - all user tables have disappeared!!
I performed the following command: sp_role “grant”, dtm_tm_role, USER
because the DB_1 is used by an application which needs the XA protocol. Is it possible that this command changed the USER´s profile and he can´t see the tables again? How can I discover what & when & how has erased my tables?
I am a newbie to Sybase and will be gratefull for any hint.