Calculated risk

Today I played a couple games of chess, but in this particular game I thought I was playing a computer for awhile until black blundered its queen after I blundered one of my knights, but then I was about to take the queen on f7 on the next move when all sudden black resigned!

He just couldn't process it in time that's why he made a major mistake, and that cost him the game while I was trying really hard not to blunder my queen? But blundering my knight paid off in the endgame which proves that sometimes blundering can pay off unlike other pieces.