MIDI not playing

Hi, I’m a new user of Cubase LE, purchased with the Alesis i02 Express audio interface.
I had sone help from a local music shop setting up my instruments, which comprise a MIDI controller keyboard (ORLA DMK7), with the MIDI signal routed into the Alesis and then into my Win7 laptop, then back out from the Alesis to my sound box (Roland U-220).
I had the whole thing working perfectly, but had to dis-assemble today, and when I put it back together I have the following problem. The audio tracks play fine, but a) I cannot get Cubase to see my incoming MIDI signal when I play the k/b (despite the MIDI IN red light flashing on the Alesis), so cannot record. In and out MIDI devies are selected for the Alesis, so I’m perplexed by that. b) When I play my previously recorded MIDI tracks, it all looks fine (the MIDI OUT light on the Alesis flashes, and the MIDI message light on the soundbox flashes), but no sound comes out of the sound box and it displays the msg “MIDI OFFLINE”.

It’s driving my mad. Any suggestions gratefully received.