No module named 'PyEMD'

Look closely at the code example from the package’s documentation:

from PyEMD import EMD

import numpy as np

s = np.random.random(100)
emd = EMD()
IMFs = emd(s)

The module name is PyEMD, not pyemd, and you must import EMD, not emd.

In fact this is exactly how you did it in your original question, and you asked why it didn’t work. Other commenters advised you to change it to from pyemd import emd, but that is incorrect. The confusion is because the module is imported as PyEMD but the package’s name is EMD-signal, while PyEMD is a different unrelated package.

In short, do pip install EMD-signal and try the exact same code that you had before, the one that previously worked well.