Why did Bitdefender automatically delete an infected file?
If an infected file is detected, Bitdefender will automatically attempt to disinfect it. If disinfection fails, the file is moved to quarantine in order to contain the infection.
For particular types of malware, disinfection is not possible because the detected file is entirely malicious. In such cases, the infected file is deleted from the disk.
This is usually the case with installation files that are downloaded from untrustworthy websites. If you find yourself in such a situation, download the installation file from the manufacturer's website or other trusted website.