That is odd since you don’t think you changed anything. On the chance you aren’t using pip in same environment…
If you use conda at all, try running the following a new cell inside your notebook where you specifically want to import:
%conda install statsmodels
If you aren’t using conda at all, try running the following a new cell inside your notebook where you want to import:
%pip install statsmodels
Restart your kernel after either of those steps and try your import again.