Unless you have auditing in place, you will need to check the default trace, but the default trace only stores so much information so you may have lost the required details if your server is a very active one.
How to post data/code for the best help - Jeff Moden[/url]
Need a string splitter, try this - Jeff Moden[/url]
How to post performance problems - Gail Shaw[/url]
Managing Transaction Logs - Gail Shaw[/url]
Troubleshooting SQL Server: A Guide for the Accidental DBA - Jonathan Kehayias and Ted Krueger[/url]