Many thanks .
And so I can't use this WebCam ?
Depends.
Did you buy this webcam and did the software come with it? Was it bought at a reputable retail store or was it bought online?
If bought online, then likely not from a reputable source, so no. Not unless you want to consider reinstalling Windows to recover your computer. Not to mention all personal files and data would be at risk of theft if you do go ahead and install it anyway, despite what avast! and other virus scanners are saying. Think identity theft and worse.
If Virus Total says a file tested as 2 out of 46 positive for malware, then it can be a possible false positive. Not so with 28/46, that file tested is most certainly a file that will compromise your system and you would likely regret your decision to install anyway. Besides, with a webcam, the bad guys can now see you as the bad software would certainly be phoning home all the time.