Not recognising MIDI keyboard, it was working before?

I recently installed Native Instruments Massive on my computer, but now my keyboard isn’t working? There’s no sign of Cubase realising that it’s all plugged in and ready to use, and I swear all my settings are the same. Can someone help me get Cubase to realise the keyboard is plugged in?
Cheers

Is it a USB keyboard or connected through a midi interface?