Use an antivirus removal tool for your earlier security software to uninstall it completely. If you can download an antivirus but cannot install it, remnants of your earlier antivirus software may be installed on your computer. Once done, use it, preferably, to run a boot-time full scan. If you do not have any other computer, boot into Safe Mode with Networking or Clean Boot State and see if you can download the antivirus software. 2] Download the security software in Clean Boot State or Safe Mode Update your existing dedicated installed security software, and then run a full scan using it.After the tool has finished running, restart your PC.If the tool finds any infections, it will identify the malware that it has found and then remove that malware from your computer. Click Next, and then follow the onscreen instructions to run the scan.Read the license agreement and accept the terms.If prompted to run the file as an administrator, click Yes.Double-click the downloaded file on the removable media.Connect the USB to the infected system.After the file download completes, remove the USB.Save the file to a USB flash drive or removable media.On an uninfected computer, download the antivirus software.

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