there is no un-delete option.
I'm sure grow diaries has a copy in a archive but good luck getting it back.
Will be easier to just start over, hopefully you saved the pictures you uploaded.
Sometimes you can find the pics under the strains page under photos, but it might only be for hidden not deleted diaries.
Eg.
growdiaries.com/seedbank/exotic-seed/honey-mints/gallery
It used to show some photos to a diary that is no longer accessible, but it seems to have removed them. The grower has pics of it in a trash can cuz it went hemi but they deleted or hid the diary so you could only see the pics and not the full diary.