aight so 1...how do you know when you accomplished your role in jungling and
2. how can you turn around a game where all lanes are retarded and dying left and right

1) When your team is getting decently fed and the opponent adc and mid carry have alot of deaths and are shut down most of the times
2) I start building damage myself in some rare-cases and carry the game through

1) Well, you're on par/outfarming the other jungler, aswell as your level.

Timing is neccessary, e.g. you KNOW which lane might or/is going to get ganked thus you go to help that lane.

You've helped lanes win. <- most obvious one eh.

Objectives as a jungler, e.g. securing your buffs every game, securing drags etc.


2. This is so damn stressful and you can't always expect yourself to turn everyone around by yourself.
I don't think it's literally possible to save EVERY LANE. But you can help, perhaps 1-2 lanes and stick to ganking those. When you divide ganks e.g. you gank top, then mid, then bot. They still die even though you ganked. So focusing on a certain lane, crush that one then move on to the next can really benefit your team. Ward up for them <- this is very important. even though "im a jungler not the support" it doesn't matter. you still need to ward and this can make a very significant change to their lanes. Pink wards help for obvious warding spots for bot aswell.

1) Lanes you've visited are winning because of you. (i.e., Camping the Enemy Veigar until your Mid Lux is 8-0 and she can tank his combo and then burst him down... or burst anyone else on their team down for that matter. Then your job is done and Lux carries you through to late game and by then the advantage is so huge they can't catch up)
2) You can't. Try to camp one or two lanes, turn them around and hope you have enough of an advantage to make up for the losing one(s).