FYI: this is NOT a duplicate!
Before running my python code I installed biopython in the cmd prompt:
pip install biopython
I then
When I came across this problem I noticed that after I installed biopython using pip install biopython the module directory in the site-packages folder was written with lowercase instead of uppercase letters. All in all, the folder was named bio instead Bio, so I just renamed the folder and everything started to work just fine. I am new to programing so I am aware this isn't the most elegant solution but it worked for me so I hope my answer will be useful to some of you. :)