i know this topic is a reular,but iv recently bought a second hand trek,which was tubeless,but the guy had a puncture and fitted an innertube in one of the wheels,so,how can i tell the difference between a normal valve and a tubeless one,and what do i need to re convert back to tubeless,i know i need the stans stuff, a valve,any special tools??? thanks

If the tyre has a tube in it won’t be a tubeless valve as the valve will be part of the tube.

What kind of rims are on the wheels? If its got a tube fitted you will need to buy a valve to fit to the wheel to run it tubeless again. You may also need some sealant depending on the tyres you use.
Then you need to learn the patience required in inflating a tubless wheel / tyre 😮
Theres a fair bit of info on the no tubes web site.
http://www.notubes.com/Movies.aspx

You’ll need a UST valve set like this one.