Jeez - thats pretty vague. If you have a picture you could post that would help, any information like the brand, is it a padlock, pin tumbler, wafer, warded?
Sounds like a privacy function lock such as that found on a bathroom or perhaps bed room door, in which case it is neither a pin, wafer, warded, or lever lock.
Aaaaah, you mean the ones that lock by pushing the inside knob in and turning it? Then you insert a metal rod, toothpick, or pretty much anything else into to open.
They are still used, and still very common for indoor locks like bathrooms and bedrooms where you really don't need the security of a regular keyed lock. That is of course unless you have a really bad room mate.
