Does A sign stating that vehicles are parked at owners risk in their parking lot mean that the proprietor is totally blameless if negligence on there part is proved?

No, a sign stating that vehicles are parked at owners' risk does not absolve the proprietor of all liability. If negligence on the part of the proprietor can be proven—for example, failing to maintain the parking lot or ensuring safety—then they may still be held accountable for damages or losses. Such disclaimers may limit liability but do not eliminate it entirely. Legal outcomes often depend on the specific circumstances and local laws.