No audio signal on one project

Wonder if anyone can help?
I can record audio tracks on all my songs apart from one particular project, in Cubase 5.
Guitars and vocals have previously been recorded on this project, but on opening it up recently, i can’t seem to get any audio input signal. I must have done something to it but I can’t figure it out. Any ideas?

Check your VST Connections… All setup correctly?

Thanks jasian, checking it out.