I have a threadless headset and I want to change it to a regular looking stem. Is it even possible to convert it to that? If yes, what will I have to do. By the way, it's a Windsor.

if you want a threaded stem...

you need a threaded fork and headset.

the nitto ct-80 is threadless, but is the closest thing ive seen to threaded looks wise. its a 1 1/8th steerer tube... i dont know what the windsor has...

By "regular" I'm gonna assume you mean a quill stem. If frame has 1" headtube, then you would need to replace the both the fork with a 1" threaded, and headset for a 1" threaded headset. If bike has a 1.125" headtube, you're kinda out of luck, as options for forks/quill stems for that size will be severely limited if at all available. Personally I'd just stick with set up bike came with, on an inexpensive Windsor. After all pros these days are all riding with threadless stems.

And someday.... believe it or not..... probably not too long from now, when all the track bikes are relegated to the dusty corners of peoples basements on top of the rollerblades,+ all bike mfrs change to some integrated/proprietary/stemandfork onesies bull****, people are gonna be retrogrouching for the halcyon days of threadless setups