The bootloader is necessary for serial programming. Without a bootloader the chip must be programmed through the ICSP connector by a programmer (USBASP).
Does the original 328 chip from the Uno still work? If so, you could put it back into the Uno and use the Uno to bootload and/or program the new 328 chip. You will need a beadboard and a few parts. Here are instrucions.
Or do a Google search for "bootload a 328 with uno" for many more tutorials on bootloading.