I Put my 2003 ford windstar in the shop for fan issues now it wont start and they say i need a computer. Why and how. Please and thank you

Hello, the engine's processor, assuming that's what you are referring to by "computer", acts to ground circuits when operating components. If somehow power is provided to a circuit that is supposed to ground, then yes - damage can be done to a processor if circuit protection fails (fuses). Unfortunately, I can't tell much from the concern description. What was the original cause of having the shop look at the van? Cooling system fans not working? What testing was performed? I can't say that I've ever seen a Windstar -- from the mid-1990's through the advent off the Freestar that replaced it -- need rewired for a fan issue. Sounds like something more is going on here, and even more than that, if the wrong path was taken and care not exercised, then damage may have been done -- that they should rectify for you. www.repairpal.com/repair-shops If you'd like to find another opinion, try a shop through that link.