i will assume (not(p v q)) ^ r means ~(P\/Q)/\R

so what you want to do first is bring the ~ in as so:

(~P/\~Q)/\R

then you want to bring the R into the (~P/\~Q) as so:

(~P/\R)\/(~Q/\R)

so now you have the correct form for a DNF, but do not have all the propositional variables in each OR'd section. So now add a Q to the first section and a P to the second one as so:

(~P/\Q/\R)\/(~P/\~Q/\R)\/(P/\~Q/\R)\/(~P/\~Q/\R)

and you're done.

hope this helps (i know i'm a bit late, but this is my first time on this forum and i found your question through google)