Hello everyone heres my lovely story.

Backing down my drive way going to work one morning and my car locks up and won't move. Engine is fine. Try and go forward just dies down and than i try to go backwards again engine dies down while I'm slowly letting the clutch out. (Handbrake is not on haha). The same afternoon after i get back from work I check the brakes to make sure they haven't ceased or are stuck on. All good in that department, i then go forward and than backwards a few times letting the car roll backwards itself and than i sort of pop out of something stopping me and than I'm free.
Now the first thing i want to know is what caused that to happen?(maybe the hill start assist?)
And also now that i drove it to see if everything's fine, I now hear a flapping or fluttering sound coming from the front even when out of gear and rolling freely. Mostly hear it around 60kph. I'm stumped with both those things.

Help is much appreciated. Thank You!
Car has 160000klms on it and manual.