Delete all files..return comp to factory settings

I've been having a few problems with the computer and haven't been able to fix it using System Restore or anything. How do I go about just deleting everything I've put on the computer, and returning all settings back to factory settings. Basically I want the computer to be the same as the day I bought it. The only problem is I don't have any of the CDs the computer came with with me because I am in between moves right now. Is there any way to do this? I have an Inspiron 5150. Thanks a lot!