gnome-tweak-tool doesn't start due to "ImportError: No module named gi" error
Little workaround found here:
sudo nano /usr/bin/gnome-tweak-tool
Change #!/usr/bin/env python to #!/usr/bin/python
My file is named 'gnome-tweaks' BTW, and it was already #!/usr/bin/python I solved my crisis by realizing that I've recently installed python3 along side python2 and set it to default. [[ python -> python3 ]]
I changed my line to
#!/usr/bin/python2
Now it works