What exactly did you do when you “reformatted” - a hard drive format?
If you now think that plug-ins are not the problem then I would suspect a problem with your computer sound device.
You can test that by rebooting into Windows Safe Mode . Audacity does not load sound devices in Safe Mode because Windows audio services do not run in Safe Mode.
Did you install 64-bit audio drivers that are meant for your specific motherboard or specific computer model? You can’t use the 32-bit audio drivers you were using before. Please see http://wiki.audacityteam.org/wiki/Updating_Sound_Device_Drivers .
If you have further questions about drivers please give the make and model number of the computer (or if you built the computer yourself, make and model number of the motherboard).
Gale