Hi YK
I am Dave, an Independent Advisor, I will help you with this . . .
Your Windows 10 is in Tablet Mode, do you want to use Tablet Mode?
If so, in the middle of the bar to the left of that Notepad window is two tiny vertical bars, click and drag that to the left of your screen
If you do not want to use Tablet Mode, depending on your version of Windows 10. here is how to take Windows out of Tablet Mode:
1
Press the Windows Key + A to open the Notification Bar
If you cannot see the Tablet Mode button, click 'Expand'
Then click the Tablet Mode button
or
2
Open the Settings App (gear icon on your Start Menu)
Go to System - Tablet, then click Advanced Tablet Settings and turn off Tablet Mode