u dint mention wat did u do b4 d problem occured so i'm assumin dat ur comp fine, but slow [misunderstood 4 not workin]
how long do u wait b4 decidin it is not shuttin down?
check how many services u got runnin
if u got lotsa services runnin, den disable d 1s dat u dont need, den ur shutdown time shud reduce
if u dont wan2 disable dem den after givin d shutdown command, wait 4 around 5 mins atlest [just 2 b sure] 4 d comp 2 shut down