How do you reset the entire computer back to a previous state through safe mode?

[yazzy]

I downloaded avg anti virus & a day later I tried logging into my side. I got all these error messages, after clicking ok to all of them the screen went blank n you cant get anywhere unless you shut it down by the button. what can I do to get it back to normal???

 

[kimsland]

How to Start the System Restore Tool from a Command Prompt

%systemroot%\system32\restore\rstrui.exe

Reference Here: http://support.microsoft.com/kb/304449/en-us