Worst case scenario, back up all data, format-reinstall OS. If nothing else works, that’s the only solution left. Hope you find a resolution!
Use a boot disk to boot to an unwriteable OS. Then run the scan and clean up any viruses. No system files will be in use so you will be able to delete or clean any file on your hard drive. You can use UBCD to create the boot disk.
Trojan or any types of viruses are really hard to remove because they are well created by computer geniuses. However, you can still remove the infection by using an antivirus software. You have to use an updated, latest, and fully licensed antivirus software to remove the infection.