Window wiped out

Hi
I tried to install window Sever r2 on my laptop which originally has a window 7
I mistakenly chose the same drive of window 7 . Finally, Window R2 overwrote the original window.This is the situation .Now I want to ask the following question:

1, How can I retrieve back the original window ?
I see there is a "window.old" folder in the new OS. I have read some web site. They say I can do sth to go back. But the problem is i bought the laptop from dell . I dont have the recovery disk. And I called the customer service . They asked to go through a "restore process". But the process would wipe out all the documents I have

2. are there any ways I can go back to window 7 without deleting my documents ?

Thanks a lot

Why not backup your documents to a blank dvd/cd, usb stick or something like https://skydrive.live.com/ and do the restore, it will be a lot safer that trying to do a restore without dataloss.

Where did you store your documents when you had win7? If they were on the windows partition, then your only chance of recovering them now is to look in the windows.old folder. If they were on a different partition, just follow z3r010's advice.