You likely installed to a different environment than the one that your Jupyter if you are having import trouble with code that should use scikit-learn. (Sometimes the easiest way around this at this time is to run %pip install scikit-learn first as a new cell in the top of the notebook where you want to use it & then restart the kernel and try the import. Keep in mind that magic symbol in front of pip is important.That is if you don’t mind yet another package installation kicking around your system. You could always uninstall the package in your terminal before trying that, if you care about only installing it in one place.)
However, what you shared is only two lines and don’t reference scikit-learn?
And something should happen if your import isn’t working. You should get a module not found error. That would be something happening. And in that case you should share that specific error traceback with us using fenced code blocks. Nothing at all happening could indicate different issues. It is hard to tell with the disjointed post you have provided thus far.
You should also share the minimal, reproducible code you are trying to run that gives the import error also using fenced in code block. See here or the last three sentences here.