Arduino Uno r3 not working properly

Hello, Some how I messed uped the bootloader of my uno. So I bought a new atmega 328p with bootloader and installed it but now I can't upload codes from my conputer. It recognizes it but it will post a error. Than I tried to burn the blink skech with the bootloader to the atmega 328p externally via a programer but now I still can't program it via my computer and the led stays on apox. 3 seconds and turns of for 3 seconds while the delay is set to 1000.

What should I do??

Arduino Unos are cheap on eBay.