Unity is not letting me build my project for windows phone because of a problem with function OnMouseDown, I tried to look for the solution but I didnt find anything useful, not even in Unity Documentation, I think the solution is Input.simulateMouseWithTouches but I am not sure how to put it in the code. Thanks for help.
Depending on your code or what you want to do, you could always use:
if (Input.GetMouseButton(0))
{...}
It will run the code inside the … area when the mouse button is clicked and/or held.