To do this, turn on or restart (if you can’t, use Ctrl + ALT + Del) your computer and press the F8 key (it varies with your PC maker, find the one that works out for you. It’s always shown briefly at Start Up) to bring up the Windows 7 or Vista boot menu.
Choose Safe Mode and boot into Windows. When you’re at the Desktop, get up a Command Prompt and type in rstrui to load System Restore. Click Next and then choose the restore point by date: pick a date where you know that you computer worked properly. Click Next and Finish to restore your computer.