As long as you're just concerned with files in a single directory (and not in files in subdirectories), there is no need to switch from ls to find . Try:
Can you qualify what you mean by "ls command not working"? Arg list too long? If so, and you can't increase that limit, you could either try breaking the command down to get fewer files ( (ls -t [a-g]*; ls -t [h-n]*; etc..) | ... ), or use find with either the -prune or -maxdepth options to prevent reading subdirectories, if that's a concern.