Vostro 5480 not recognizing external monitors

[Jess_10]

am using Vostro 5480 window 10 and trying to connect to Dell U2410 External monitor via HDMI cable, but it cannot detect the monitor and shown No HDMI Cable

 

[Saga Lout]

Is there a Function key with screen icons that you're supposed to use to extend the display? Was the last part of your post an actual error message?