Windows 7 log files

I'm pretty sure my roomate tried to access my PC while I was at lunch. He had no password so had to turn it off after failing to log in.Is there a log file where i can check the time this happened?

Hi Stephen Richter – Welcome to Microsoft Answers Community.

Use Event Viewer in Windows®. To open Event Viewer follow the
steps below:

1. Press  + R and type“eventvwr.msc” and pressEnter or clickOK.  

 Security note: If UAC is enabled, then you’ll get a UAC prompt on screen. Please specify
credentials or permission to pass the UAC elevation.

2. Click Yes to give the Event Viewer permission to run.
3. Expand Windows Logs and select  Security from the left side.
4. In the middle of the Event Viewer you’ll see Number of events,
and what has happened etc, whether it was a log-in or a logoff which
was performed.

I hope you find this information useful. If you need any further assistance,
please feel free to contact me and let me know.

I hope this information was helpful…

Have a nice day…

Best regards,
Fisnik