If you are a Trezor wallet user, chances are you are unable to sign any transactions on Stellar Term or any Stellar wallet / exchange that lets you use a hardware wallet like Trezor. This means users will not be able to send or do any transactions directly from this hardware wallet. The Trezor team is aware of this and working on resolving this issue.
There are few ways to still sign transactions. Most recommended way is to buy a Ledger hardware wallet, import your mnemonic phrase and sign transactions with it. Ledger also has a native Stellar application and does not depend on Stellar Term, Stellar Laboratory or Account Viewer.
Second way to get around this issue is by using a software wallet like Freighter which is made by Stellar Development Foundation. You can easily import your Trezor’s seed phrase into Freighter and sign transactions easily. Keep in mind software wallets are not as secure as hardware wallets.
So, what caused this issue? Well, Trezor churned out an update few days back that contains a lot of changes and that broke ability to sign Stellar transactions. If you are still on previous firmware, do not update till this issue is resolved.