''attempt to reconnect''

​i was in an intro ( coop vs ai ) game suddely i got ''attempt to reconnect'' thing but then i immediately open chrome youtube and everything can conncet but the game wont connect like 2 mins later so i had to force closing ,i can still open my league of legends client after that like normal. then i check theres no such game in my match history?

game score was like (draven 7/2/3) destroyed 2 bottom turrets and on the way to the third then this happended