dock causing all kinds of problems, help!

i entered this into terminal to add a recent applications stack

defaults write com.apple.dock persistent-others -array-add '{ "tile-data" = { "list-type" = 1; }; "tile-type" = "recents-tile"; }'
killall Dock

when i entered killall Dock, the dock disappeared and never came back. i tried to restart to see if it would come up after that but when i restart everything closes and then my computer remains on my desktop background and wont restart. finally i did a hard restart and after that the dock will still not come up. i tried to kill the dock again but i get the error "No matching processes belonging to you were found." also, im having other random problems like expose wont work anymore.

how can i fix this?

all i can say is use your OSX disc and boot up with it, once that is done, format your hard drive using Disk utility. Once that is done reinstall Mac OSX and errthing should be great

i just ran my osx disc and did archive and install and my dock still doesnt show up, but when i type killall Dock into terminal it doesnt say "no mathing processes belonging to you were found" anymore

do i have to reformat my hard drive?

Yes you have killed your Dock stone dead and keep out of Terminal unless you know exactly what you are doing.

But first ** into System Preferences and see if Dock is selected there. You may be lucky.