Get windows original cd and reinstall it again ...don't choose " repair" , but reinstall..it wll reinstlall on the same directory, same root, then it'll make some corrections to all the missing files , u'll be prompted for that, so just click " yes or ok..;it'll take 20 may b at least 30 minutes .
don't try to download te svchost file cause it's a root process,it's part of the heart services and it's istalled as a package so even if you deleted the file you can't reinstall it manually only the windows installer program can do that properly.