Why Trezor wallet is showing zero balance
There are a few reasons why your Trezor wallet might be showing a zero balance. Here are some of the most common causes:

You have imported the wrong recovery seed. When you set up your Trezor wallet, you were given a 24-word recovery seed. This seed is used to generate all of your private keys. If you import the wrong recovery seed, your Trezor wallet will not be able to access your funds.
You are typing in the wrong passphrase when accessing a hidden wallet. Trezor wallets can be protected with a passphrase. If you have enabled a passphrase, you will need to type it in every time you want to access your funds. If you type in the wrong passphrase, your Trezor wallet will not be able to access your funds.
Your funds are in a passphrase-protected (hidden) wallet, but you are accessing the standard wallet. If you have enabled a passphrase, your funds will be stored in a hidden wallet. If you try to access your funds without using the passphrase, your Trezor wallet will not be able to see them.
You have not enabled the coin in Trezor Suite settings. Trezor Suite is a software that allows you to manage your Trezor wallet. If you have not enabled the coin that you want to access in Trezor Suite settings, your Trezor wallet will not be able to see it.
How to fix a zero balance on Trezor wallet
If your Trezor wallet is showing a zero balance, you can try the following steps to fix it:

Check your recovery seed. Make sure that you have the correct recovery seed. If you are not sure, you can restore your Trezor wallet from your recovery seed.
Check your passphrase. If you have enabled a passphrase, make sure that you are typing it in correctly.
Check your Trezor Suite settings. Make sure that the coin that you want to access is enabled in Trezor Suite settings.
If you have tried all of these steps and your Trezor wallet is still showing a zero balance, you can contact Trezor support for help.

Additional tips
Here are a few additional tips to help you avoid a zero balance on your Trezor wallet:

Write down your recovery seed and keep it safe. Your recovery seed is the only way to restore your Trezor wallet if you lose your device or forget your passphrase.
Use a strong passphrase. Your passphrase should be at least 12 characters long and contain a mix of letters, numbers, and symbols.
Keep your Trezor device safe. Do not share your recovery seed with anyone and do not store it in an online location.
By following these tips, you can help to protect your funds and avoid a zero balance on your Trezor wallet.