Not sure why you uninstalled FTM2006.
You should have a FTM2012 ICON on your Desktop. Actually, unless you deleted it, you should also see a FTM2012 ICON on the Windows Tool Bar.
Guessing that you still have FTM2012 Installed, you should be able to click on Start, Programs, All Programs, and select Family Tree Maker 2012.
When that opens, you would want to Open an Existing file, an option in the Plan Workspace, New Tree, then navigate to where that FTW file is located and FTM2012 will open that file.