Should i give up on the girl i like that says that she will nvr accept.?

i had this really big problem with the girl that i like says that she cant ever think of accept me. i didnt do anything that made her unhappy or upset her and then she starts to avoid me when she saw me. i know that she feels guilty but she even block me when i used the messenger. is there any reasons? sometimes i jus feel like i wan to give up.