missing midi controller

I’m running an akai lpk25 into AI7 and have bee!n using it fine for a couple of days, until it now shows up as missing in the input window of the track controller. then when I try to assign it. it’s not on the pull down. Nor does it show in the device manager. Midi playback is unaffected.
Also! my playback is mono and when I try to pan a track it silences it I have a stereo output channel set up but only one gauge moves on playback.
any help gretfully received. am getting to grips with the world of digital audio after a 10 year gap!