There's no universal means of informing the world that a loved one has died. Their family might print a death notice in the local newspaper or post the news online, or they might simply rely upon word of mouth. It's certainly possible that you might be unaware that the person in question has in fact passed away until weeks or even months after it happened. It's an undeniable tragedy, and this can be exacerbated by the fact that you were unable to attend the funeral because you didn't know about it. You will still want to express your deepest sympathies to the grieving family, but what's the best way to go about this?
A Message of Sympathy
You might think that the timing of your sympathies could feel somewhat delayed, but it will still be appreciated. Make contact with the family of the deceased. Don't dwell upon the fact that your message has arrived well after their loved one has been farewelled, but you should still acknowledge it. This should be as simple as starting your message by saying that you've only just heard about the death — you don't need to press the point any further. Under no circumstances should you lament the fact that nobody reached out to tell you, as this was just an unfortunate oversight.
Flowers and Donations
Flowers are traditional, but not mandatory, and can conceivably be unhelpful after the event. The family is attempting to adjust to the loss, and flowers can be a tangible reminder of that loss. Instead of sending flowers with your message of sympathy, you should ask if the deceased requested donations to a charity in lieu of flowers. Although the donation is in commemoration of the deceased's life, it's going to be appreciated at any time, and making the donation after their funeral doesn't detract from its sentiments.
Visiting the Final Resting Place
You can tactfully enquire about whether the deceased was buried or cremated. If there is a burial site, this can be your opportunity to bring flowers. You will likely find it helpful to visit their final resting place to say your own goodbye since you weren't at the funeral. If they were cremated, ask if the ashes were scattered, as you might want to visit this spot to say goodbye.
Watching the Funeral
You can also ask if the funeral was live-streamed. This is increasingly common and is intended for those who were not able to be physically present. Many funeral homes offer this service, and it can be possible to view the funeral at a later stage if you wish to do so. The funeral home will generally just direct you to where the video has been archived online. Contact the funeral home to learn more.
You might have had every intention of going to the funeral had you known about it. Don't dwell upon this, and simply say goodbye in your own way, which isn't any less significant because it's a little delayed.