If you accidentally downloaded malicious software or virus, it is important to take the following steps:

1. Immediately disconnect the internet connection to your computer.


2. Scan your computer with an anti-virus and anti-malware program.


3. Remove any malicious files or viruses that were identified.


4. If your anti-virus software does not detect any malicious files, disconnect the computer from the internet again, and attempt a manual removal.


5. If no malicious files are present, you can try to use a system restore to fix possible errors, or reinstall the operating system.