Hi i have a monitor or graphics card problem

My monitor works just fine until it suddenly doesnt display anything and its in sleep mode. I tried to plug it at my mobo and it worked. Then then one day it doesnt work again so i switched it again to my graphics card then it worked. Then again on the other day it wont work so i switched it AGAIN to the mobo. I have been switching it for about 3 weeks now, i cant play games and i cant do heavy duty works requiring gpu when im i switch to mobo. pls help me *sorry for the english tho*