You received a perfectly legitimate response, which was to take it to the bike shop and let them look at it. The cumulative body of knowledge on this forum has no freakin' idea what you're talking about when you say the brakes just slid. It makes zero sense to any of us. V-brakes don't work, then mysteriously not work, then work again. There has to be a reason they "slid", whatever that means, and you are failing to get that point across. We're not the idiots here. Put that in your newb pipe and smoke it.