Who Used Ur PC In Your Absence

First Go to
Start > Run > eventvwr.msc

Events are stored in three log files:
1. Application.
2. Security and
3. System.

These logs can be reviewed and archived. For our purposes we want the System log. Click on System in the left-hand column for a list of events. Look for a date and time when you were not in your computer. Double click on the information it will show you all the system events in detail.

You can also use this log to see how long someone was on the computer.
Just look at the time the computer was turned on and turned off for that day.