You've organised a ride with someone and confirmed it, but now they're not replying. This can happen and it's unfortunate but not all is lost.
The first thing to do is to try and call your carpooler. A call is a lot harder to miss or ignore so you're more likely to get through to them this way.
In case you do not get an answer within a reasonable time period we recommend that you cancel the ride and find someone else to carpool with.