There is nothing you need to do within Forecaster to work with the backup - it is a SQL Server process. Once your database is restored to the backup, you should be able to log into Forecaster as usual and it will be as if you hadn't made any changes.
As for changing your rollups to ranges... you should be able to create the ranges where you need them. However, since Forecaster doesn't allow you to have the same codes in a rollup more than one time, you'll need to remove the posting-level items from the rollup, then you can add the range that encompasses them.
So, if you have a summary that has something like:
and you want to change that to be a range, you would delete the posting items, 100,101 and 102. Then insert a new range under 'TOT' which is the range of 100 to 102.
You can also create a brand new rollup if you want to do this separately and leave the other rollups intact. When you've got it all set, you can decide whether to remove the old rollup or not.
I hope this helps. MSX Group is here to help you with all of your Forecaster needs, so if you need assistance, please contact us!