check exact size of your database not right click on database then property and check size not from option.

SELECT DB_NAME(database_id) AS DatabaseName,

Name AS Logical_Name,

Physical_Name, (size*8)/1024 SizeMB

FROM sys.master_files

WHERE DB_NAME(database_id) = 'AdventureWorks'

GO

re-create indexes for those tables.

I think you configured backup with append option. So just configured new backup with default options.

-Arun

What error code are you getting?

-Arun

Can you tell what step you are performing for Rebuild Index?