Completely stopped fermenting, can't restart

I have a 6 gallon batch of mead (15lbs of clover) which I added hops to about 4 months ago. Racked and moved a couple times then before I went away for a month in early May I checked the gravity and it was 1.015. Racked and checked gravity again last week and it was stil 1.015. Added some a packet of D-47 and also added 3tsp of yeast energizer and 1 tsp of nutrient. It still hasn't changed. Any ideas on where to go from here. Was actually hoping to get this one into some bottles when I got back to get another braggot going.

What is the temperature of the room? What yeast did you pitch the first time? Did you add nutrients early in the fermentation? What is the pH of the mead?

Assuming that there are no obvious problems in the answers to those questions I would choose a very aggressive yeast (something like EC-1118) and add 1 cup of your stalled mead to a starter you have made with the yeast (say 1 cup of apple juice). If the cup of mead shows that it is fermenting (You measure the gravity of the apple - mead 2 cup mix) then after about 2 hours you add 2 cups of the mead to this active mix. If that is still actively fermenting, after two or three hours you then add 4 cups of mead. You see the pattern? You are adding from the stalled batch to the active batch and you are adding the stalled batch in quantities that the starter can apparently handle. And you repeat this process until you have added all the stalled batch to the new batch (You do NOT add the fresh yeast to the stalled batch!). But before you do all this you want to make sure that the pH is not too low, there is enough air in the mead, there is enough nitrogen in the mead and the temperature is optimal for the yeast...

Temp is about 70 degrees. Don't have any way to take the pH so will have to work on that one

You can get pH test strip from your local pet store that sells fish. Not very precise, but you'll have a better idea if it's a pH problem.

What was your starting gravity? Id imagine that 3 months of active fermentation would be more than enough time for any yeast to run its course.

Still haven't made it anywhere to get ph strips. Hopefully Monday or Tuesday. Starting SG was around 1.06 or so, fermented nicely for a while then hit a wall.

Your starting gravity should have been closer to 1.090 assuming 6 gallons and 15 lbs of honey (2.5 lbs of sugar per gallon) . If you thoroughly mixed the water and honey and your are very confident that the gravity was 1.060 then the problem may be with your hydrometer. Can you beg borrow or buy another hydrometer and check the gravity?

Finally got some test strips today and right where I would expect. Around 4.4. Still sitting a 1.02 where it has been for 2 months, I did put a bit of hops in it but it smells horribly sweet and tastes like crap.

Okay so I did as was suggested, started about a gallon of new mead in a primary, got it going good with some champ. yeast, a day later I added about a 1/4 gallon, still was churning nice, next day another 1/4 gallon, and the same the following day. It stopped actively fermenting on day 4 and has sat that way for the past 3 days..

bernardsmith's 100% right about that hydrometer reading being way off. To get a better idea of gravity estimates, use the mead calculator. While it may not be 100% correct (honey's sugar content varies), it will give you a pretty good idea of where you should be. The one on GotMead? is having some trouble at the moment, but there are some mirrors listed on the sidebar at /r/mead over at Reddit (Google works too, I suppose).

Also, every time you rack, you are leaving lot of yeast behind. If you are not far enough through (or done with) primary when you rack, you may end up with too little yeast in suspension to finish it up in a timely manner. I mean, it will eventually, it'll just take a long time. If you racked several times during primary, then this could be a major reason that your ferment slowed down so much in the first place.

Finally, if it stopped after 4 days since adding in that starter, check your hydrometer - it might be done! 15-20 points is nothing to healthy yeast!

Hydrometer works fine on all the other batches that are going so I am certain that isn't it and the current batch is sitting right around 1.02 so it is far from done. It tastes like drinking the sweetest drink you've ever had so again, it is far from being done fermenting.

As I stated I have added yeast now 2 additional times without racking so that wouldn't be the issue.