A settlement from the other driver's insurer is voluntary: they settle when they believe it is more cost effective for them to settle rather than fight (e.g. if you look like you will sue and it would be an expensive case to contest and/or that they may lose). Them withdrawing a settlement offer does not mean you cannot seek compensation, but you would do so by suing the at-fault driver and proving in court 1) that was at fault (e.g. driving negligently or carelessly) in causing the accident and 2) that he caused certain provable injuries or costs to you.  You can only sue for actual, provably injuries or costs, however, not for what might be discovered or occur in the fugure, so you cannot sue until and unless some injuries are found or there are medical costs.