You don't have to enter Windows to choose a restore point.
You can get to it via the recovery. (i think it's called recovery. Like on Android)
When starting up the computer, you have to hit a certain F key when you see the posting screen (a screen that looks kinda like this: http://i.stack.imgur.com/yfGCk.jpg
The F key should be ether F8 or F7.
You want to find this:
From here you can choose troubleshoot -> advanced options -> system restore.
Hope this help.