sense of taste gone since Gastric Bypass

I am 3 and a half weeks post op and nothing tastes right.  When will my sense of taste come back.  I am so thirsty and can't seem to quench my thirst cause everything tastes bad. 

Sounds like you are in Ketosis, which is not a bad thing.  You can get some strips to test for it at the drug store.

It will get better, I promise.

It was nearly 9 months before I started to enjoy any flavors.  

For drinking, try different flavors and even temperatures.  I went to my childhood favorites of sweet tea and green koolaid and found a winner.  I used splenda instead of sugar and I was home-free.