Please specify if you are using Tabbles Cloud or Lan. It is not clear from you post.
If you are using lan, please follow this: tabbles.net/blog/video-how-to-migrate-the-tabbles-database-to-a-different-sql-server-instance/
(in particular the script at the end)
If you still have problems, try to connect with Management Studio as described here:
and tell me if you can connect.
if you are using tabbles Lan and lost your password, you can find it in the “users” table (login with management studio).