I've got a Hyper 7 TQ nitro car and the threads on the head button are stripped. I can find loads of head buttons with a turbo plug but can't find a standard one. Are there any head buttons for other brands that would fit?

You would need to know what the bore of the engine is, what depth the head button protrudes into the cylinder, combustion chamber diameter/shape/depth, etc. if you want to get picky. The most important is the bore diameter and depth into the liner being the same. Quite honestly, I would suggest putting a helicoil in it and try to be 200% more careful to not strip it out again.

Knowing what brand of engine you have and size would be helpful as well.

If you tell me the diameter of the cylinder, and if possible also the bore (check that they are the same), I can help you find out. The best way to do this is to use a calliper (I use an electric one), which will give you all the necessary information as well as the dimensions or other data needed.