No Audio

I have a project that for some reasons the VST Instruments are not playing anymore. I checked another project and no problems. Please advise me what could be going on with this issue. Thank you!

You could post your project here (but zip it up before) and we could have a look what’s wrong with it.
Or if it is too sensitive, you could mail it to ‘u dot stoermer at steinberg dot de’; full confidentiality guaranteed.

I would also suggest simply doing Play > Playback Template and re-applying the default ‘HSSE+HSO (Pro)’ playback template, which might be enough to kick things back into gear.