Why can't I log in on my computer?

Mmmm yess I tried and its been happening for like 3weeks now

To start System Restore using the Command prompt, follow these steps:

1. Restart your computer, and then press and hold F8 during the initial startup to start your computer in safe mode with a Command prompt.
2. Use the arrow keys to select the Safe mode with a Command prompt option.
3. If you are prompted to select an operating system, use the arrow keys to select the appropriate operating system for your computer, and then press ENTER.
4. Log on as an administrator or with an account that has administrator credentials.
5. At the command prompt, type %systemroot%\system32\restore\rstrui.exe, and then press ENTER.
6. Follow the instructions that appear on the screen to restore your computer to a functional state.

thats may happen by so many reason,like viruses,bad settings,new software an so on … so,if u cant logged in with out dong s.th wrong,its better to load ur computer in safe mode,and restore ur settings to few days ago,,70% every thing going alright after restart :D

do you mean login to this site or your actual pc cus the way im reading it your saying you cant see the login for this site.

the sign up is on teh left and login on the right from teh sign up/login link.