2011 Ford Everest the 4 x4 switch dont engage,

Mitchell On-Demand is one online service manual company but access is pretty expensive. Instead, go to the top of this page, point to "Service and Repair", then click on "Manuals" to go to a site where you can buy a subscription for just your vehicle. Normally I only recommend manufacturer's service manuals over Haynes or Chiltons manuals, but this site gives you the manufacturer's stuff, plus a lot of other information such as recall notices, service bulletins, and in some cases, solutions to common problems.