how to download logic 10.2.4 again after hard disk crash ?

torbjörn112 wrote:

how to download logic 10.2.4 again after hard disk crash ?

You can't.

Apple only allows you to purchase/download/re-download the current version of Logic Pro and any other Apple apps. There is no way to get earlier versions.

You'll need to get it from your backup.

You can just drag the app back into your applications folder and go from there.