May I suggest you give a little more information, to help people help you.
E.g. What VR plugins do you have enabled?
What VR system do you have connected?
Have you modified any project settings to enable Start in VR for example?
Have you started steamvr or your headset’s client (in my case I start the Oculus client BEFORE starting up my unreal engine VR project?
So, what have you done, so people can work out what you haven’t done.
Also, make sure your GPU and VR headset drivers are up to date.