If a token isn't showing in MetaMask, it's usually not lost funds but funds that have arrived without being displayed. Confirm receipt on a block explorer, switch to the send chain's network, and import the token by its contract address.
A wrong-network transfer can usually be recovered if the destination is a self-custody wallet (add the correct chain or import the key), but it's generally unrecoverable if sent to an exchange deposit address on an unsupported chain (only some exchanges offer paid, case-by-case help).
Your seed phrase is the only way to restore a self-custody wallet, so if you never recorded it, operator or third-party recovery is fundamentally impossible. But if the wallet app is still on your device, your assets are held at an exchange, or you still have your hardware wallet, you may be able to reach your funds without the seed.