Background:
I have a site built in ASP.NET with Sql Server 2005 as it's database. The site is the only site on a Windows Server 2003 box sitting in my clients server room. The client is a local school district, so for data security reasons there is no remote desktop access and no remote Sql Server connection, so if I have to service the database I have to be at the terminal. I do have FTP access to update ASP code.

Problem:
I was contacted yesterday about an issue with the system. When I looked in to it, it seems a bug that I had solved nearly a year ago had returned. I have a stored procedure that used to take an int as a parameter but a year ago we changed the structure of the system and updated the stored procedure to take an nvarchar(10). The stored procedure somehow changed back to taking an int instead of an nvarchar.

There is an external hard drive connected to the server that copies data periodically and has the ability to restore the server in case of failure. I would have assumed that somehow an older version of the database had been restored, but data that I know was inserted 7 days and 1 day before the bug occurred is still in the database.

Question:
Is there anyway that the structure of a Sql Server 2005 database can revert to a previous version or be restored to a previous version without touching the actual data? No one else should have access to the server so I'm going a little insane trying to figure out how this even happened.

Any ideas?