Well.. so my plant is about 3 weeks old and sitll small and it had some dead leaves that were killed by a diease or some shit.. and i cut off the whole leaf + steam of it only the Big center steam is leaf.. will it grow back?
If you have some leaves left on the plant it will provide itself nutrients via photosynthesis - light absorption. If you cut the only leaves it had off it had then you will need to start over - I would think...
Even if it's just a stem there is still a chance it will recover. If you are providing enough light you should know within a couple of days if it is truly dead. It is a weed, and weeds are very resiliant.