How do I restore Windows7 to factory specs with no CD?

Recently my AV found a threat and after I removed it and restarted, I got an error "Failure to initialize MainWidow" and everything runs slower now. Thought it might be a problem with the AV, so I removed it and reinstalled. Didn't help and I could not get the updates, I had to change my AV. I had MS security essentials, now I am using Norton 360(I had to pay for a new licence as mine was outdated). Windows update will not run at all. When explorer or MSExcel, or Windows mail stops responding, my only option is to end the task in task manager. Once I had to pull the power cord to restart (battery is out due to a separate problem). On one of the restarts after it first happened I could not even enter my windows password. I think my only option is to reload windows7 and bring my laptop back to factory specs, except I do not have a Windows7 DVD, just one for the drivers. Any ideas on how I can fix this?