No - Avast’s File Shield scans executable files before they are allowed to run. So yes it was prevented from running.
If you mean that you deleted the file from quarantine ?
Files in the quarantine are safe, they encrypted, the file name changed so they can’t be accessed from outside of quarantine. So you have time to ask questions before taking drastic action.
Since you don’t give any information on the detection, file name, location and malware name I can’t speculate or investigate on why it might have been detected.