A myself & 2 friends had this problem too.
Where you'll accept the game, but it won't launch the game & your client only says "Game in Progress".
The work-around that's worked so far for us is using the Task Manager (CTRL+ALR+DEL). When you open Task Manager, you might find a program that's "Not Responding" (it will have a League Icon next to it, I actually don't know what that program is called). You'll want to end that task & when you do that, the client should give you a RECONNECT Button.
The game will attempt to relaunch & it should work.
Hopefully this helps.