@Kishor O ,
Seems like we don't have direct way to restore them(if you delete widget from the dashboard), could try below options
1)Go to sys_update history table and look for dashboard grid canvas pan and try to revert to previous version (make sure you find appropriate record before revert) if this wouldn't work
2)Since its OOB dashboard, refer the dashboard in the lower instance (dev or QA) and add the same widegt and layout in the Prod.
