IDLE doesn't recognise installed packages

[Daniel Tangemann]

hi,
I've recently downloaded and installed python 3.6. (I had already also 2.7 and 3.2 on my computer) Initially pip was looking in the wrong directory to install to, so I changed that. then it had trouble installing matplotlib, so I decided to get rid of the older versions of python, which srewed things up even more. now scrips that I had written (in 3.6), that were running without errors before, aren't working anymore. I tried reinstalling python, and I tried the repair option multiple times as well. when I look into the python folder, I can see the modules that I have installed (and that I import into those scripts), but the IDLE doesn't see them! what's even more weird, is that "pip list" doesn't bring up anything but pip itself, while typing "pip install matplotlib" returns a message that it's already installed. how do I fix this?
cheers