Warp

Generally, when something is grayed out (blocked) it's because you are not at a state where it is available, such as being on the wrong layer, selection not active, unsupported mode, etc... 

Posting a screen capture of your entire screen can be helpful.

Make sure you have what you want to warp selected and that you are on the right layer.

Be careful with the Warp tool as sometimes it comes of as kind of amateurish.  But it all depends on how you use it.

Use Warp on what kind of Layer/s exactly?

Is a Selection active?

Can you show a screen shot? Please show entire screen.