SvcHost.exe (the real one) infected with trojan, how to remove???

The SvcHost.exe file in the System32 folder has been infected with a trojan, How do I remove it?? I am very scared and don't want to lose everything on my computer. I'm not very familiar with virus removal at all so I don't know what (if anything??) can be done about this. My antivirus, AVG free antivirus, can't remove it

I think the infection came from the UNi Xonar custom drivers I downloaded for my sound card. Part of the installer was detected by AVG as a virus but I thought it was a false positive since I had downloaded older versions of the driver with no issues so I added an exception for it.