Why wont my van start i have changed starter and battery and it turns but wont start

Sounds like a bad starter. It's not extending to spin the flex plate. Use this link to find a good shop near you. https://repairpal.com/repair-shops Alex

Have a helper attempt to start engine - look under hood to see if engine is rotating. IF so - the timing belt has failed and there is no compression - therefore the engine spins freely. And of course it will not start.