iphone dead and wont restore

my iphone5 turned of suddenly without any reason just like other. initially the hard reset worked. but this problem started happening everyday and yesterday the hard reset stopped working as well. so i connected it to my pc and itunes said that iphone hai gone in recovery mode. so i tried to restore it. itunes downloaded the software for the restore but now while installing it just says waiting for iphone and wont do anything else. what should i do????