My game crashed all of the sudden while in the game and i had to reconnect

The thing is the crash didnt show me ,,wait for the program to respond,, or any other option to choose from like the usual appcrash does. It just closed and i missed alot of xp, my botlane was pretty much destroyed and i couldnt do anything since i was like 4 levels behind. Im mostly upset because this made me loose Lp and its unfair