Question: how to restore tbk file in tally?
Answer: Go to Gateway of Tally > F3 : Cmp Info > Restore to view the Restore Companies screen.
Destination - The folder path where your company data is to be restored. ... 
Source - The folder path where the backup file is stored. ... 
Select the required companies from the List of Companies . ... 
Press Ctrl+A to restore the data backup.