Hardly anyone has this problem.
Have you force quit Audacity in Windows Task Manger, shown hidden files and folders, navigated to C:UsersAppDataRoamingAudacity then tried editing audacity.cfg so that it only has this text?
NewPrefsInitialized=1
[VST]
Enable=0
Rescan=0
If you have done that then the problem is probably with security programs on your computer not allowing other programs to open, or a defective sound card or set of sound card drivers.
What is the make and model number of your sound card? Have you updated its drivers to the latest drivers supplied by the motherboard or computer maker?
Also see this topic for more ideas about what you could try:
Audacity 2.0.3 .
Gale