Contentstore is only part of the story, you need to have the matching PostgreSQL database. If you did the default install and if you have backed up the installation directory then there is a folder alf_data and that has the contentstore and the PostgreSQL files. If you have moved things around or did not do a default install then you will need to bring back the alf_data folder from wherever that was. It is also possible that the PostgreSQL database was not in alf_data, again, by default it is but it can be moved.