I suggest the first thing you'll need to do is find out why she's using "restore". This copies a backup over the top of the current company file. Any data in the current database that does not exist in the backup will disappear.
The main cause for repeated use of restore that I've seen is transferring the database between two computers, one at the business premises and another at home for after-hours processing. Doing this means you have to be careful managing the process so data is only ever changed on one computer at a time. However it should not cause any loss of older records.
Quickbooks doesn't close yearly accounts, you just generate reports by date range to produce figures for any given year. However to limit the size of company file this can cause, previous years data can be compressed. If this has been done, individual transactions can no longer be accessed, you can only generate category totals in reports. This could give the impression data has been lost. If that's what has happened, in order to access old transactions and be able to generate reports like weekly or monthly activity, you need to be able to temporarily restore an older backup from before the year's accounts were compressed.
I hope she has always stored away regular backups of the company file so that this sort of thing can be handled. If a proper backup regimen has not been followed, there can be a world of pain. Another thing to check is if audit tracking is turned on. That records every change that is made to the company file, and could prove important if forensic recovery is needed or obviously in case of an audit occurring.
It's been a good few years since I've used QuickBooks, so that's probably about all I can suggest at first thought, someone else will no doubt be more up-to-date and know more than I do. And there are also QuickBooks resources and forums you could check out e.g.:http://community.intuit.com/quickbookshttp://forums.quickbooksusers.com/index.php