How to fix blank System Tray icons  

• Backup Registry
• Go to Start > Run type regedit and hit OK
• HKEY_CURRENT_USER\Software\Classes\Local Settings\Software\Microsoft\Windows\CurrentVersion\TrayNotify.
• Delete the values IconStreams and PastIconsStream
• Open up the Task Manager (Ctrl + Shift + Esc), go to the Processes tab, select explorer.exe and click End Process.
• Open the Applications tab and click New Task at the bottom-right of the window.
• In the message box that pops up type in explorer.exe and hit OK
• after all these step if issue is still not solved then use the mention blew and scan PC
• Run a check using anti-malware tools, like Adwcleaner or MalwareBytes, just in case.