install() function in .install file won't run?

So after fiddling with the admin and front end of my module for awhile, turning it off and on, off and on I reached the point where I need to create a .install file for it and an install method.

I go about creating it, having it generate required content types for what my module does. The problem is the install() method never runs at all. I've disabled my module and re-enabled it numerous times and it just won't run?

Do I need to do this in an update() method since I've already enabled my module once or twice? Or is there some module cache which needs to be cleared in the db?

Thanks in advance!

st.