Can't Reinstall OS X

[RayVille]

I was planning on selling my macbook so i erased the hard drive but I accidentally erased the startup disk and when I try to reinstall OS X EL CAPITAN it tells me "this item is temporarily unavaiable please try again later"

 

[CoastalOR]

It would help to know which model and year Mac? Any backups?

Assuming you have a new enough Mac to support internet recovery (Option-⌘-R) then use that to install the OS.
https://support.apple.com/en-us/HT204904
https://support.apple.com/en-us/HT201314