This isn’t a direct answer to the question, but this seems like you’re asking for advice. Learning coping mechanisms and therapy can help with feelings such as this because you’ll always come across moments where you’ll be happy. Even as someone with depression I have my happy moments. It may seem bleak and difficult after living a happy moment and feeling like you’ll never quite grasp that feeling again, but life changes and things happen. It’s best to just enjoy the moments and look forward to the moments that will eventually come next.