It is likely that the Wisconsin Division of Motor Vehicles (DMV) will be able to help you track down the at-fault person's insurance carrier, if he has one. The WI DMV checks for insurance coverage on all drivers listed on an accident report. So hopefully you called the police to your accident scene to take a report.

If the DMV finds that a motorist involved in an accident is uninsured, the other parties involved in the accident are notified. Those who are injured or have property damage can report their injuries or damages to the DMV. The Wisconsin safety responsibility law helps protect those who suffer damages in accidents caused by uninsured motorists by first taking away their driver license and vehicle registration if the uninsured motorist is at-fault and did not pay for the damages they caused.

So either way, if the at-fault party did or did not have insurance at the time of the collision the DMV should be able to help you so that your damages can be taken care of by the person who caused the accident.