Your seed is the most important part of your Sia node because it controls access to your wallet and files. You need to keep it safe, but there are a few tools you have available to find or fix your Sia seed.
These commands can be used directly in siac. In Sia-UI, open the Terminal from the toolbar on the top of the app.
If Sia is already unlocked
You might use a custom password to access Sia. If you do, you don't often type your seed in and you may need a refresher on what it is.
Unlock your wallet and open the Terminal. Type wallet seeds.