There is only one shutter control that's TV = Time Value or the amount of time the shutter is open. Set your camera to either the P = Program or Full Auto modes and the shutter will be "normal". What's happening is your shutter is too fast for the lighting conditions so your photos appear dark.
I usually roll my eyes at those posts that say "Read your manual". Honestly, I've never read though any of mine. I've thumbed through them when I have a specific question but that's about it... In this case though, it's probably the best solution to your problem.
Shutter Priority Mode (Tv) allows the user to set shutter speed while the camera matches the appropriate aperture size for the given lighting conditions. If you have selected a shutter speed that is too fast and the camera is unable to find the correct aperture size (ran out of settings) for the amount of available light, you should see a warning (usually something will flicker in the status screen). You either slow down shutter speed, raise ISO or both to solve the problem. If the picture remains too dark for you, make sure that exposure compensation (lightmeter) is set to 0 (zero) then adjust to the plus side to satisfaction. A zero setting on the lightmeter is your correct (normal) exposure setting.
