[Koha] Reservoir vs catalog

Hi everyone, We are an independnat library which recently installed Koha. We cataloged our c. 800 books, on a local system on a PC. Yet, we had to move the catalog to an other computer (and cloud) and the whole list have been lost in the process since the digital access path has been changed. However, we have been able to tranfer (and find) our 800 books , which are gathered in the reservoir (name, author, ISBN, etc.), but we cannot find the catalog, which lists each item of our library and which  allows us to do loans, etc.  Do you know how can we recover such pieces of information?  Where can we find the catalog? Thank you very much. Jehane Zouyene