Question Why does my phone only charge when it's on, but doesn't when it's off

[Preben19]

My phone was showing something like; connected with the OTG cable, go to settings and disconnect OTG, meanwhile OTG cable isn't connected.
That's what it showed before it stopped charging

 

[helpstar]

Which laptop brand and model and phone/android version is it?

Do you mean, that your laptop will only charge your phone while the laptop is on? Have a look at the USB ports of your laptop, the ones with a flash symbol or similar should be on while the laptop is off.
like the right USB port in this picture:
https://cloud.addictivetips.com/wp-content/uploads/2016/05/usb-port-1.jpg