www.tracfone.com does give you the option of reactivating a phone. Note that you will have lost any previous minutes and days that were on the phone and that you will have a new phone number. You lose your number when the phone goes inactive.
You will need to buy airtime in order to activate the phone. If you will go to this site first, you'll see a list of promo codes. These change all the time, so use the most current. Might as well get all the minutes you can, even if you don't expect to need them. Also, if your phone has double minutes for life, free minutes added with a promo code will not double.http://preprepaid.com/currenttracfonebonus.php