Hi Friends. Lollipop Is Released for Zenfone 4.5 From 28 Of this Month. Its not a OTA update , Its a offline update so You have to Download Files and manually upgrade.
Attention::: For installing Update to lollipop Your Phone must Latest update of Kitkat.
Upgrade too lollipop
To downgrade From Lollipop to kitkat . Download the Firmware Below . It will downgrade To latest kitkat