I poured fiber powder down the drain last night thinking when I turn on the water and garbage disposal it would flush down the sink. Wrong it became a big slimy mess and now my garbage disposal is just humming and the drain won't drain. I did scoop all the water and slime out of the sink but it must be clogged still and when you run water and turn the disposal on nothing moves down the pipes. HELP!! 1

Turn the power off to the disposal and see if you can't disconnect the pipes and clean them out. MAKE SURE THERE IS NO POWER TO THE DISPOSAL BEFORE YOU MESS WITH IT AT ALL.
If you get in there and the mess is just too bad to fix yourself, you'll have to call a plumber.

The clog is in the disposal and the p trap before it connects to another sink so you could try plunging it. Fill the sink about 1/4 full and really do a hard plung down and then back up smartly. Try this 4 - 5 times. Warm water helps. If this doesn't work your will be removing those drain pipes. The one coming from the disposal turning down is held by one screw above the pipe.