No Sound from Mac Mini after OS X Server Reinstall
Go to ~/Library/Preferences and trash your com.apple.systemsound.plist file. Drag it right into the trash. Empty trash and restart your Mac.

A new plist file will generate automatically, look for the speaker/sound icon in your Finder menu. If that doesn't resolve the issue, try Command ⌘-Option ⌥-P-R again during reboot and make sure you hear the Apple chime at least two times for a full recycle.