If you are talking about a bookmarks backup. Use Bookmarks > Organize Bookmarks -> Import & Backup - Restore = Choose file....

Export is HTML format which needs to be imported.

I have the same problem

Use Bookmarks > Organize Bookmarks -> Import & Backup - Restore = Choose file....

i have backup of 6 .json files

when i choose 1st one

This will replace all of your current bookmarks with the backup. Are you sure?

then i click on ok

but there is no chage in my new bookmark

please help

thanks in advance

Make sure that the JSON backup has .json file extension.

See also http://kb.mozillazine.org/Locked_or_damaged_places.sqlite