First of all, don't panic. It's not the end of the world (either way).
Take account of your situation:
Do you still have the device your wallet is on and access to your wallet?
Fantastic! You can create another wallet and generate a new seed that you can send your coins to. But FIRST:
- Send your coins to an exchange of your choosing
- Ensure that you see your coins in your exchange account completely transfer over
- Reset your wallet device
- Proceed to create a new wallet on the same device and generate a new seed
(See 10-Step Beginner's Guide To Bitcoin Wallet Set Up & Security and start with step 2)
You might be asking, do I REALLY have to. I still have access to my wallet and keys don't I?
Well, yes. But, if the device that your wallet is on ever goes caput, you're out of luck. Your seed is the only way to recover your wallet once it fails and electronics don't last forever.
So yes, you really have to. Even if you still have an extra copy of your seed, you don't know where that other copy might be and who might find it in the future.
Besides, it will always be on your mind that your seed somewhere out there for someone to find (or steal). Generating a new seed will let you sleep at night without worrying about your seed being exposed.
Now if the answer is no, you don't have access to your wallet and you lost your seed, you can panic. Unfortunately, your coins are gone until you can find your seed again.
Self-custody isn't meant to be easy nor convenient. It's about complete control over your finances and that's a huge responsibility.
It takes time and effort to consider the logistics and come up with a well thought out plan for your future self.
After you finish panicking, realize it's not the end. You can always start over. Lessons learned for the next time.