I have a couple of drawings that I did back around 2008 that I can not open. If I open the folder containing the CAD file, I can see the elevations that I drew on the thumbnail preview of the file. Once I double click the file to open, AutoCAD starts the process of opening up the file but opens up to the default drawing1. I do not get any corruption errors or nothing. Has anyone else ever had this problem?

That thumbnail is only a snapshot in time and may not be a true representation of the actual drawing.  The fact that Drawing1.dwg opens when you try to open a different DWG file is troubling however.