how can we get the restore in sql server 2000 of sql server 2005 data
You can't restore data from sql 2005 to 2000 only if you generate scripts with sql server 2000 compatibility. If you want create and restore backup can't do.
I do not think this is possible. You can't go from 2005 to 2000, what you would have to do is install SQL 2005 Express then restore to that and you should be able to manage the backup from there.
If you only need the database structure you can generate scripts for the entire database.
Use RedGate SQL Compare and RedGate SQL Data Compare to push the tables and data from SQL 2005 to SQL 2000.
You may be able to script the whole database from SQL 2000 compatibility mode, but getting the data requires something besides a backup and a restore. You could try bulk saving and bulk loading data, too...
I recently found myself in a similar position on a client site. I came across an article on the MSDN SQL Server Forum (second response from top) with a detailed walk-through on this issue.
I ran into a few issues with scripting users & had to hack my way through it a little bit, but it was a great starting point for me.