Email setup on iPhone 4S deleted contacts, reminders, and calendar dates When I synced my phone to microsoft exchange account, all of my contacts, reminders, and calendar dates were erased. 

This is what I did: 


Settings
mail, contacts, calendars
add account
microsoft exchange
put in my school email


The settings were found and my email synced. I went to place a call and all of my contacts were deleted. I do not have a mac and nor did i do anything using my iTunes account. 

How can I get all of my contacts, calendar dates, and reminders back and keep my email set up on my phone?
When you created the Exchange account, I think it ask you if you want to keep your contacts or replace them with the ones on the Exchange. And it surely works the same for calendar events and reminders.

It appears you asked your phone to replace your already existing contacts list with the empty one from Exchange.

Your best shot to get your contacts back is to restore a previous backup, and then, when re-setting your phone, be careful to what it's asking you.