@GH Lee -

have you tried the procedures at the bottom of this help document: https://help.miro.com/hc/en-us/articles/360017572614-How-to-Restore-a-Deleted-Board

Kiron

I have already read about the document. But there is no trash button in the image I attached.

I meant the instructions at the bottom of the article:

For those who are in despair because you accidentally deleted your work. There is a lightning icon positioned below which you can restore.  
 

@Alex Junus - Thanks for sharing.

To read more about this, the lighting bolt is the Activity List - here’s the Help Center article:

https://help.miro.com/hc/en-us/articles/360017730913-Activity-List