No navigation buttons or drop down bar Lollipop topic

So i tried a custom ROM to try and fix the lag and slowness of the G3 to no avail
i then decided to go back to stock so i downloaded UK 16G D85510A_00.kdz stock ROM

Flashed it with flashtool all fine although an old version booted and working fine

I then connected phone to LG PC suite and proceeded with the update to Lollipop 5.0 as i cant find a stock 5.0 KDZ file

now running 5.0 kernel 3.4.0
build No lrx21r.a1417604035
Software version v20E

Problem is as in title i have absolutely no on screen navigation buttons and i also cannot drag down notification bar
No icons or clock displayed at top nothing just full 100% screen usage
so as soon as i go into any menu i cant go back
volume buttons don't work but if i long press volume down camera opens

This is beyond weird