ruler unable to activate

I have windows 10 and windows 8 both bought with licence and I have installed libreoffice latest version.
The vertical ruler doesnt appear at all, can you help me please.
My team viewer id is : 345 085 646 and password: pppppp. You are free to enter my computer to take a look

Thank you !

[Edit: added win10 + lo5 tags]

Please verify this option: Menu/Tools/Options/LibreOffice writer/View