If you had a trojan or virus some other attack on your machine and you believe the integrity of your wallet is compromised then we recommend:
- Use your 12-word Daedalus wallet recovery phrase to recover your wallet on a machine that you trust
- Then you create another wallet and choose a different 12-word Daedalus wallet recovery phrase
- Move your ada from your old wallet to your new wallet.
- Discontinue using your old wallet.
It would be best if you did this as soon as possible to reduce the chances of losing your ada.
You can download the Daedalus wallet here: https://daedaluswallet.io/#download
Don' forget that ada does not reside only on your machine. It is in the blockchain, which means that if your machine is unavailable your ada is still available. So your if your machine was attacked, this does not necessarily mean that your ada is gone. Your 12-word Daedalus wallet recovery phrase, however, is critical to maintaining control of your ada. If an attacker finds out your 12-word Daedalus wallet recovery phrase then you may lose your ada. Daedalus does NOT store your 12-word Daedalus wallet recovery phrase on your machine in a way that is easy to read even for an attacker.
See also Tips for Staying Safe Online