If you are a jungler and every lane is losing

Be the enemy jungler.

Then every lane is winning.

farm like you've never farmed before and hope you spot a chance to help out a lane

Step 1: be fed ? Step 2: oneshot everyone except Step 3: ??? Step 4: Profit Source: I was Braum in this scenario

When i'm winning top and the other lanes are losing, y does laning phase have to ever end

proceed to go around the map and holding up the minion waves(like going in behind the turrets in top and bot lane) to stop any more cs from coming in allowing you to divert their attention from the worst lanes and come stop you, allowing your allies to catch up.