If you keep your PC on for long periods or make it hibernate instead of shut down you may lose track of when last you restarted Windows. If you are curious and want to know when last Windows was restarted you can do so using the command line.
- Press Windows Key + R to open the run dialog box
- Type cmd and press Enter
- In the command line type net stats srv and press Enter
- The line that starts “Statistics since” will indicate the last time Windows was restarted
How to find Windows uptime? – Microsoft Support