C# Path Parameter Implementation in REST API

I'm in need of a C# developer with deep .NET Framework expertise. My RESTful API currently accepts query parameters but fails to handle path parameters. It needs to be modified to correctly process path parameters within the URL. The response format of the API is strictly JSON, so experience with JSON is a must. There's no need for any authentication mechanism at this point, so basic coding skills along with problem-solving and debugging skills are key.