They had paper though not as durable as the modern one. Papyrus had the same function, but it decays over few decades and things written on it should be rewritten. If you have a few centuries of war and low literacy like in the western parts of the Roman empire, there is noone to renew the pagan texts and they get lost. The eastern empire bothered only with the texts compatible with christianity while the arabs kept those compatible with islam.
The printing press might've been useful though.