Why can't I restore the master component?

Why is there no button to restore my main component after it is deleted?

Hi Iris,
Thanks for reaching out to the community!
Can you double check if you can find another Instance for that delete Component, and if you are able to see the option to 'Restore Component"?

If you’re not able to find an Instance, then I’d suggest duplicating a previous version history to see if you can save an old copy of the file where the component exists. You can find more information on how to do this in this article here: https://help.figma.com/hc/en-us/articles/360038006754-View-a-file-s-version-history
If not, I’d recommend you to re-create the component again by copying and pasting it from the duplicate into the library and publishing it. Hope this helps!