Minecraft multiplayer not working

today minecraft multiplayer isnt working properly for some people and i'm one of those people. I was on a server where i was recently made admin and they had to restart server they did i tryed to re join but guess what it said. cant verify username! and im not very happy about that its kinda pissed me off cause i wanted to finish a
pixel art diamond sword i was making. but now i cant because of multiplayeer not working for me i tryed updating didnt work. tryed joining over and over again didnt work so now im pissed at how i cant go on any server so now i have to play single player til my multiplayer starts to work again and that has just pissed me off alot and i think notch or jeb should fix this problem.

-Rynod16