Perform a clean reinstallation by following the instructions below.

Uninstalling VEGAS Pro / VEGAS Movie Studio will remove all audio and video templates, as well as all custom settings, from your computer.

• Unplug all external USB and Firewire devices from your computer.
• Temporarily pause your antivirus software.
• In Windows, go to "Start" > "Control Panel" > "Programs and Features" and uninstall the program.

After uninstalling the software, delete the following folders manually:

VEGAS PRO EDIT

• C:\ProgramData\VEGAS\VEGAS_Pro_15_Edit 
  
• C:\ProgramData\VEGAS\VEGAS_Pro_16_Edit 
• C:\ProgramData\VEGAS\VEGAS_Pro_17_Edit 
• C:\ProgramData\VEGAS\VEGAS_Pro_18_Edit 
• C:\ProgramData\VEGAS\VEGAS_Pro_19_Edit 
• C:\ProgramData\VEGAS\VEGAS_Pro_20_Edit 

VEGAS PRO

• C:\ProgramData\VEGAS\VEGAS_Pro_15 
• C:\ProgramData\VEGAS\VEGAS_Pro_16 
• C:\ProgramData\VEGAS\VEGAS_Pro_17 
• C:\ProgramData\VEGAS\VEGAS_Pro_18 
• C:\ProgramData\VEGAS\VEGAS_Pro_19 
• C:\ProgramData\VEGAS\VEGAS_Pro_20 

VEGAS PRO SUITE

• C:\ProgramData\VEGAS\VEGAS_Pro_15_Suite 
• C:\ProgramData\VEGAS\VEGAS_Pro_16_Suite 
• C:\ProgramData\VEGAS\VEGAS_Pro_17_Suite 
• C:\ProgramData\VEGAS\VEGAS_Pro_18_Suite 
• C:\ProgramData\VEGAS\VEGAS_Pro_19_Suite 
• C:\ProgramData\VEGAS\VEGAS_Pro_20_Suite 

The next step requires deleting one or more Windows registry keys. The registry is a very sensitive part of Windows. If you are not comfortable working with advanced configuration and system settings in Windows, ask an administrator to help you. 

Enter "Regedit" in the Cortana search field to  open the Registry Editor.

Delete all the Vegas entries from the following registry sections:

Up to version 19

• HKEY_CURRENT_USER\Software\ Sony Creative Software 
  
• HKEY_LOCAL_MACHINE\SOFTWARE\ Sony Creative Software 
• HKEY_CURRENT_USER\Software\Wow6432Node\Sony Creative Software 
• HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Sony Creative Software 

From version 20

• HKEY_CURRENT_USER\Software\Vegas Creative Software 
  
• HKEY_LOCAL_MACHINE\SOFTWARE\Vegas Creative Software 
• HKEY_CURRENT_USER\Software\Wow6432Node\Vegas Creative Software 
• HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Vegas Creative Software