SQL Server TempDB Growth issue
If you have the default trace configured, and if the change was recent enough, you might be able to find the change.  The default trace only maintains a certain amount of trace, but I have found unexpected changes by examining its contents.

See: http://msdn.microsoft.com/en-us/library/ms175513(v=sql.105).aspx

This describes how to read the default trace so that you can research problems.

There is no backward looking tool to find database growth and other changes. 

If you want to have a persisted history of changes you will need to periodically query the needed data and store it in a database table.  With SQL Server 2012 Change Tracking can also answer questions like this.