Icons on the home screen were distorted, background dissapeared windows were all grey (like generic linux windows), I changed the theme which fixed that but there are millions more problems.. Conversations wont open so i can send or read any txts, web crashes saying out of memory (as do most other apps).. Only 21 of 2000 or so mp3's are showing in the media player, and file manager doesn't even show the internal memory, on the microsd card... So i've completely messed it up..

Will i have to send it away? will flashing it help?

Have you tried re-inserting the microsd card?

Only one way to find out.

Just wondering whether it could cause more harm then good..

Given how little seems to be working at the moment, it's hard to see how it could make things worse.

I'd definitely try reinserting the microSD card and rebooting first. It sounds like you have a software problem that may have been triggered by a poor/lost connection to the microSD card.

Removed microsd, reflashed using NSU.. Same problem.. Pretty much everything i open says low memory (if it opens at all)

I am thinking the drop knocked lose some memory. What does free show, what does df show?

since it is memeory issue you might have more luck reflashing emmc

I second this, it definately sounds like you've got a memory chip broken loose. Pretty sure you need to service it. :/