Why is life being stressful

Well hi I am a 20 year old girl I am writing this cuz i have no one to open up about what i feel cuz no one will understand me. Lately everything is being so hard on me . I've changed so much from last year or from two years ago. I went from a happy , motivated, lovely, kind girl to a anxious, cold hearted, stressed girl. I know anyone will say 'why should we care about how are you' . But I can't do anything anymore, I can't seem to find the fun side to anything, I can't even have the slightest interest on someone. It's been almost a year since i fell i love deeply but it didn't last. I hope it did though. And ever since the day me and him broke up I've never felt the same person again , i lost all my feelings about any man . And still i am not able to feel that kind of attraction towards a man the way I felt it before . I swear idk what to do . Day by day im turning into a stranger.