System restore as it was the 1st day

Hello,

I have dell lap top and windows7 home basic operating system , because my computer was slow and certain application was not functioning i restored the system with restore point being 4 days back(21 sep 2010).but i noticed that all the previous dates or restore point have vanished (before 21st). system condition is still not satisfactory as the 1st day. Now i want restore the system 1.5 months back but there is no display of those dates. Kindly suggest how should i restore the system as it was in the first day(day of purchase) that is the state from the factory itself