@Suraj - Is your Miro account profile, i.e., the email you sign in with, a member of multiple teams/spaces? If so, perhaps you are on the wrong team dashboard - click the team icons on the left-vertical bar:

@Suraj -

You can also search your browser history and access the boards using their unique URLs that way assuming you have been using Miro through a web browser...

Kiron

Good point, @Kiron Bondale.

@Suraj  - You can also try the Miro search function → https://help.miro.com/hc/en-us/articles/360012140959-How-to-search-in-Miro